--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xml/en/docs/njs/reference.xml	Mon Sep 24 19:24:04 2018 +0300
@@ -0,0 +1,1281 @@
+<?xml version="1.0"?>
+
+<!--
+  Copyright (C) Nginx, Inc.
+  -->
+
+<!DOCTYPE article SYSTEM "../../../../dtd/article.dtd">
+
+<article name="Reference"
+        link="/en/docs/njs/reference.html"
+        lang="en"
+        rev="9">
+
+<section id="summary">
+
+<para>
+<link doc="index.xml">njs</link> provides objects, methods and properties
+for extending nginx functionality.
+</para>
+
+</section>
+
+
+<section id="core" name="Core">
+
+
+<section id="string" name="String">
+
+<para>
+There are two types of strings:
+a <literal>Unicode string</literal> (default) and
+a <literal>byte string</literal>.
+</para>
+
+<para>
+A <literal>Unicode string</literal> corresponds to an ECMAScript string
+which contains Unicode characters.
+</para>
+
+<para>
+<literal>Byte strings</literal> contain a sequence of bytes.
+They are used to serialize Unicode strings
+to external data and deserialize from external sources.
+For example, the <link id="string_toutf8">toUTF8()</link> method serializes
+a Unicode string to a byte string using UTF8 encoding:
+<example>
+>> '£'.toUTF8().toString('hex')
+'c2a3'  /* C2 A3 is the UTF8 representation of 00A3 ('£') code point */
+</example>
+The <link id="string_tobytes">toBytes()</link> method serializes
+a Unicode string with code points up to 255 into a byte string,
+otherwise, <literal>null</literal> is returned:
+<example>
+>> '£'.toBytes().toString('hex')
+'a3'  /* a3 is a byte equal to 00A3 ('£') code point  */
+</example>
+Only byte strings can be converted to different encodings.
+For example, a string cannot be encoded to <literal>hex</literal> directly:
+<example>
+>> 'αβγδ'.toString('base64')
+TypeError: argument must be a byte string
+    at String.prototype.toString (native)
+    at main (native)
+</example>
+To convert a Unicode string to hex,
+first, it should be converted to a byte string and then to hex:
+<example>
+>> 'αβγδ'.toUTF8().toString('base64')
+'zrHOss6zzrQ='
+</example>
+
+<list type="tag">
+
+<tag-name id="string_bytesfrom"><literal>String.bytesFrom(<value>array</value>
+| <value>string</value>, <value>encoding</value>)</literal></tag-name>
+<tag-desc>
+(njs specific) Creates a byte string either from an array that contains octets,
+or from an encoded string (0.2.3).
+The encoding can be
+<literal>hex</literal>,
+<literal>base64</literal>, and
+<literal>base64url</literal>.
+<example>
+>> String.bytesFrom([0x62, 0x75, 0x66, 0x66, 0x65, 0x72])
+'buffer'
+
+>> String.bytesFrom('YnVmZmVy', 'base64')
+'buffer'
+</example>
+</tag-desc>
+
+<tag-name><literal>String.fromCodePoint(<value>codePoint1</value>[, ...[,
+<value>codePoint2</value>]])</literal></tag-name>
+<tag-desc>
+Returns a string from one or more Unicode code points.
+<example>
+>> String.fromCodePoint(97, 98, 99, 100)
+'abcd'
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.concat(<value>string1</value>[, ...,
+<value>stringN</value>])</literal></tag-name>
+<tag-desc>
+Returns a string that contains the concatenation of specified
+<literal>strings</literal>.
+<example>
+>> "a".concat("b", "c")
+'abc'
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.endsWith(<value>searchString</value>[,
+<value>length</value>])</literal></tag-name>
+<tag-desc>
+Returns <literal>true</literal> if a string ends with the characters
+of a specified string, otherwise <literal>false</literal>.
+The optional <literal>length</literal> parameter is the the length of string.
+If omitted, the default value is the length of the string.
+<example>
+>> 'abc'.endsWith('abc')
+true
+>> 'abca'.endsWith('abc')
+false
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.fromBytes(<value>start</value>[,
+<value>end</value>])</literal></tag-name>
+<tag-desc>
+(njs specific) Returns a new Unicode string from a byte string
+where each byte is replaced with a corresponding Unicode code point.
+</tag-desc>
+
+<tag-name><literal>String.prototype.fromUTF8(<value>start</value>[,
+<value>end</value>])</literal></tag-name>
+<tag-desc>
+(njs specific) Converts a byte string containing a valid UTF8 string
+into a Unicode string,
+otherwise <literal>null</literal> is returned.
+</tag-desc>
+
+<tag-name><literal>String.prototype.includes(<value>searchString</value>[,
+<value>position</value>]))</literal></tag-name>
+<tag-desc>
+Returns <literal>true</literal> if a string is found within another string,
+otherwise <literal>false</literal>.
+The optional <literal>position</literal> parameter is the position
+within the string at which to begin search for <literal>searchString</literal>. 
+Default value is 0.
+<example>
+>> 'abc'.includes('bc')
+true
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.indexOf(<value>searchString</value>[,
+<value>fromIndex</value>])</literal></tag-name>
+<tag-desc>
+Returns the position of the first occurrence
+of the <literal>searchString</literal>
+The search is started at <literal>fromIndex</literal>.
+Returns <value>-1</value> if the value is not found.
+The <literal>fromIndex</literal> is an integer,
+default value is 0.
+If <literal>fromIndex</literal> is lower than 0
+or greater than
+<link id="string_length">String.prototype.length</link><value></value>,
+the search starts at index <value>0</value> and
+<value>String.prototype.length</value>.
+<example>
+>> 'abcdef'.indexOf('de', 2)
+3
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.lastIndexOf(<value>searchString</value>[,
+<value>fromIndex</value>])</literal></tag-name>
+<tag-desc>
+Returns the position of the last occurrence
+of the <literal>searchString</literal>,
+searching backwards from <literal>fromIndex</literal>.
+Returns <value>-1</value> if the value is not found.
+If <literal>searchString</literal>  is empty,
+then <literal>fromIndex</literal> is returned.
+<example>
+>> "nginx".lastIndexOf("gi")
+1
+</example>
+</tag-desc>
+
+<tag-name id="string_length"><literal>String.prototype.length</literal></tag-name>
+<tag-desc>
+Returns the length of the string.
+<example>
+>> 'αβγδ'.length
+4
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.match([<value>regexp</value>])</literal></tag-name>
+<tag-desc>
+Matches a string against a <literal>regexp</literal>.
+<example>
+>> 'nginx'.match( /ng/i )
+'ng'
+</example>
+</tag-desc>
+
+<tag-name id="string_padend"><literal>String.prototype.padEnd(<value>length</value>
+[, <value>string</value>])</literal></tag-name>
+<tag-desc>
+Returns a string of a specified <literal>length</literal>
+with the pad <literal>string</literal> applied
+to the end of the specified string (0.2.3).
+<example>
+>> '1234'.padEnd(8, 'abcd')
+'1234abcd'
+</example>
+</tag-desc>
+
+<tag-name id="string_padstart"><literal>String.prototype.padStart(<value>length</value>
+[, <value>string</value>])</literal></tag-name>
+<tag-desc>
+Returns a string of a specified <literal>length</literal>
+with the pad <literal>string</literal> applied
+to the start of the specified string (0.2.3).
+<example>
+>> '1234'.padStart(8, 'abcd')
+'abcd1234'
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.repeat(<value>number</value>)</literal></tag-name>
+<tag-desc>
+Returns a string 
+with the specified <literal>number</literal> of copies of the string.
+<example>
+>> 'abc'.repeat(3)
+'abcabcabc'
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.replace([<value>regexp</value>|<value>string</value>[,
+<value>string</value>|<value>function</value>]])</literal></tag-name>
+<tag-desc>
+Returns a new string with matches of a pattern
+(<literal>string</literal> or a <literal>regexp</literal>)
+replaced by a <literal>string</literal> or a <literal>function</literal>.
+<example>
+>> 'abcdefgh'.replace('d', 1)
+'abc1efgh'
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.search([<value>regexp</value>])</literal></tag-name>
+<tag-desc>
+Searches for a string using a <literal>regexp</literal>
+<example>
+>> 'abcdefgh'.search('def')
+3
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.slice(<value>start</value>[,
+<value>end</value>])</literal></tag-name>
+<tag-desc>
+Returns a new string containing a part of an
+original string between <literal>start</literal>
+and <literal>end</literal> or
+from <literal>start</literal> to the end of the string.
+<example>
+>> 'abcdefghijklmno'.slice(NaN, 5)
+'abcde'
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.startsWith(<value>searchString</value>[,
+<value>position</value>])</literal></tag-name>
+<tag-desc>
+Returns <literal>true</literal> if a string begins with the characters
+of a specified string, otherwise <literal>false</literal>.
+The optional <literal>position</literal> parameter is the position
+in this string at which to begin search for <literal>searchString</literal>.
+Default value is 0.
+<example>
+>> 'abc'.startsWith('abc')
+true
+> 'aabc'.startsWith('abc')
+false
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.substr(<value>start</value>[,
+<value>length</value>])</literal></tag-name>
+<tag-desc>
+Returns the part of the string of the specified <literal>length</literal>
+from <literal>start</literal>
+or from <literal>start</literal> to the end of the string.
+<example>
+>>  'abcdefghijklmno'.substr(3, 5)
+'defgh'
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.substring(<value>start</value>[,
+<value>end</value>])</literal></tag-name>
+<tag-desc>
+Returns the part of the string between
+<literal>start</literal> and <literal>end</literal> or
+from <literal>start</literal> to the end of the string.
+<example>
+>> 'abcdefghijklmno'.substring(3, 5)
+'de'
+</example>
+</tag-desc>
+
+<tag-name id="string_tobytes"><literal>String.prototype.toBytes(start[,
+end])</literal></tag-name>
+<tag-desc>
+(njs specific) Serializes a Unicode string to a byte string.
+Returns <literal>null</literal> if a character larger than 255 is
+found in the string.
+</tag-desc>
+
+<tag-name><literal>String.prototype.toLowerCase()</literal></tag-name>
+<tag-desc>
+Converts a string to lower case.
+The method supports only simple Unicode folding.
+<example>
+>> 'ΑΒΓΔ'.toLowerCase()
+'αβγδ'
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.toString([<value>encoding</value>])</literal></tag-name>
+<tag-desc>
+<para>
+If no <literal>encoding</literal> is specified,
+returns a specified Unicode string or byte string as in ECMAScript.
+</para>
+
+<para>
+(njs specific) If <literal>encoding</literal> is specified,
+encodes a <link id="string_tobytes">byte string</link> to
+<literal>hex</literal>,
+<literal>base64</literal>, or
+<literal>base64url</literal>.
+</para>
+<example>
+>>  'αβγδ'.toUTF8().toString('base64url')
+'zrHOss6zzrQ'
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.toUpperCase()</literal></tag-name>
+<tag-desc>
+Converts a string to upper case.
+The method supports only simple Unicode folding.
+<example>
+>> 'αβγδ'.toUpperCase()
+'ΑΒΓΔ'
+</example>
+</tag-desc>
+
+<tag-name id="string_toutf8"><literal>String.prototype.toUTF8(<value>start</value>[,
+<value>end</value>])</literal></tag-name>
+<tag-desc>
+(njs specific) Serializes a Unicode string
+to a byte string using UTF8 encoding.
+<example>
+>> 'αβγδ'.toUTF8().length
+8
+>> 'αβγδ'.length
+4
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.trim()</literal></tag-name>
+<tag-desc>
+Removes whitespaces from both ends of a string.
+<example>
+>> '   abc  '.trim()
+'abc'
+</example>
+</tag-desc>
+
+<tag-name><literal>String.prototype.split(([<value>string</value>|<value>regexp</value>[,
+<value>limit</value>]]))</literal></tag-name>
+<tag-desc>
+Returns match of a string against a <literal>regexp</literal>.
+The optional <literal>limit</literal> parameter is an integer that specifies
+a limit on the number of splits to be found.
+<example>
+>> 'abc'.split('')
+[
+ 'a',
+ 'b',
+ 'c'
+]
+</example>
+</tag-desc>
+
+<tag-name id="encodeuri"><literal>encodeURI(<value>URI</value>)</literal></tag-name>
+<tag-desc>
+encodes a URI by replacing each instance of certain characters by
+one, two, three, or four escape sequences
+representing the UTF-8 encoding of the character
+<example>
+>> encodeURI('012αβγδ')
+'012%CE%B1%CE%B2%CE%B3%CE%B4'
+</example>
+</tag-desc>
+
+<tag-name><literal>encodeURIComponent(<value>encodedURIString</value>)</literal></tag-name>
+<tag-desc>
+Encodes a URI by replacing each instance of certain characters
+by one, two, three, or four escape sequences
+representing the UTF-8 encoding of the character.
+<example>
+>> encodeURIComponent('[@?=')
+'%5B%40%3F%3D'
+</example>
+</tag-desc>
+
+<tag-name><literal>decodeURI(<value>encodedURI</value>)</literal></tag-name>
+<tag-desc>
+Decodes a previously <link id="encodeuri">encoded</link> URI.
+<example>
+>> decodeURI('012%CE%B1%CE%B2%CE%B3%CE%B4')
+'012αβγδ'
+</example>
+</tag-desc>
+
+<tag-name><literal>decodeURIComponent(<value>decodedURIString</value>)</literal></tag-name>
+<tag-desc>
+Decodes an encoded component of a previously encoded URI.
+<example>
+>> decodeURIComponent('%5B%40%3F%3D')
+'[@?='
+</example>
+</tag-desc>
+
+</list>
+</para>
+
+</section>
+
+
+<section id="core_json" name="JSON">
+
+<para>
+The <literal>JSON</literal> object (ES 5.1) provides functions
+to convert njs values to and from JSON format.
+<list type="tag">
+
+<tag-name><literal>JSON.parse(<value>string</value>[,
+<value>reviver</value>])</literal></tag-name>
+<tag-desc>
+Converts a <literal>string</literal> that represents JSON data
+into an njs object (<literal>{...}</literal>) or
+array (<literal>[...]</literal>).
+The optional <literal>reviver</literal> parameter is a function (key, value)
+that will be called for each (key,value) pair and can transform the value.
+</tag-desc>
+
+<tag-name><literal>JSON.stringify(<value>value</value>[,
+<value>replacer</value>] [, <value>space</value>])</literal></tag-name>
+<tag-desc>
+Converts an njs object back to JSON.
+The obligatory <literal>value</literal> parameter is generally a JSON
+<literal>object</literal> or <literal>array</literal> that will be converted.
+If the value has a <literal>toJSON()</literal> method,
+it defines how the object will be serialized.
+The optional <literal>replacer</literal> parameter is
+a <literal>function</literal> or <literal>array</literal>
+that transforms results.
+The optional <literal>space</literal> parameter is
+a <literal>string</literal> or <literal>number</literal>.
+If it is a <literal>number</literal>,
+it indicates the number of white spaces placed before a result
+(no more than 10).
+If it is a <literal>string</literal>,
+it is used as a white space (or first 10 characters of it).
+If omitted or is <literal>null</literal>, no white space is used.
+</tag-desc>
+</list>
+</para>
+
+<para>
+<example>
+>> var json = JSON.parse('{"a":1, "b":true}')
+>> json.a
+1
+
+>> JSON.stringify(json)
+'{"a":1,"b":true}'
+
+>> JSON.stringify(json, undefined, 1)
+'{\n "a": 1,\n "b": true\n}'
+
+>> JSON.stringify({ x: [10, undefined, function(){}] })
+'{"x":[10,null,null]}'
+
+>> JSON.stringify({"a":1, "toJSON": function() {return "xxx"}})
+'"xxx"'
+
+# Example with function replacer
+
+>> function replacer(key, value) {return (typeof value === 'string') ? undefined : value}
+>>JSON.stringify({a:1, b:"b", c:true}, replacer)
+'{"a":1,"c":true}'
+</example>
+</para>
+
+</section>
+
+
+<section id="crypto" name="Crypto">
+
+<para>
+The Crypto module provides cryptographic functionality support.
+The Crypto module object is returned by <literal>require('crypto')</literal>.
+</para>
+
+<para>
+<list type="tag">
+
+<tag-name><literal>crypto.createHash(<value>algorithm</value>)</literal></tag-name>
+<tag-desc>
+Creates and returns a <link id="crypto_hash">Hash</link> object
+that can be used to generate hash digests
+using the given <value>algorithm</value>.
+The algorighm can be
+<literal>md5</literal>,
+<literal>sha1</literal>, and
+<literal>sha256</literal>.
+</tag-desc>
+
+<tag-name><literal>crypto.createHmac(<value>algorithm</value>,
+<value>secret key</value>)</literal></tag-name>
+<tag-desc>
+Creates and returns an <link id="crypto_hmac">HMAC</link> object
+that uses the given <value>algorithm</value> and <value>secret key</value>.
+The algorighm can be
+<literal>md5</literal>,
+<literal>sha1</literal>, and
+<literal>sha256</literal>.
+</tag-desc>
+
+</list>
+</para>
+
+
+<section id="crypto_hash" name="Hash">
+
+<para>
+<list type="tag">
+
+<tag-name><literal>hash.update(<value>data</value>)</literal></tag-name>
+<tag-desc>
+Updates the hash content with the given <value>data</value>.
+</tag-desc>
+
+<tag-name><literal>hash.digest([<value>encoding</value>])</literal></tag-name>
+<tag-desc>
+Calculates the digest of all of the data passed using
+<literal>hash.update()</literal>.
+The encoding can be
+<literal>hex</literal>,
+<literal>base64</literal>, and
+<literal>base64url</literal>.
+If encoding is not provided, a byte string is returned.
+</tag-desc>
+
+</list>
+</para>
+
+<para>
+<example>
+>> var cr = require('crypto')
+undefined
+
+>> cr.createHash('sha1').update('A').update('B').digest('base64url')
+'BtlFlCqiamG-GMPiK_GbvKjdK10'
+</example>
+</para>
+
+</section>
+
+
+<section id="crypto_hmac" name="HMAC">
+
+<para>
+<list type="tag">
+
+<tag-name><literal>hmac.update(<value>data</value>)</literal></tag-name>
+<tag-desc>
+Updates the HMAC content with the given <value>data</value>.
+</tag-desc>
+
+<tag-name><literal>hmac.digest([<value>encoding</value>])</literal></tag-name>
+<tag-desc>
+Calculates the HMAC digest of all of the data passed using
+<literal>hmac.update()</literal>.
+The encoding can be
+<literal>hex</literal>,
+<literal>base64</literal>, and
+<literal>base64url</literal>.
+If encoding is not provided, a byte string is returned.
+</tag-desc>
+</list>
+</para>
+
+<para>
+<example>
+>> var cr = require('crypto')
+undefined
+
+>> cr.createHmac('sha1', 'secret.key').update('AB').digest('base64url')
+'Oglm93xn23_MkiaEq_e9u8zk374'
+</example>
+</para>
+
+</section>
+
+</section>
+
+<section id="njs_api_timers" name="Timers">
+
+<para>
+
+<list type="tag">
+
+<tag-name id="cleartimeout"><literal>clearTimeout(<value>timeout</value>)</literal></tag-name>
+<tag-desc>
+Cancels a <literal>timeout</literal> object
+created by <link id="settimeout">setTimeout()</link>.
+</tag-desc>
+
+<tag-name id="settimeout"><literal>setTimeout(<value>function</value>,
+<value>ms</value>[, <value>arg1</value>, <value>argN</value>])</literal></tag-name>
+<tag-desc>
+Calls a <literal>function</literal>
+after a specified number of <literal>milliseconds</literal>.
+One or more optional <literal>arguments</literal>
+can be passed to the specified function.
+Returns a <literal>timeout</literal> object.
+<example>
+function handler(v)
+{
+    // ...
+}
+
+t = setTimeout(handler, 12);
+
+// ...
+
+clearTimeout(t);
+</example>
+</tag-desc>
+
+</list>
+</para>
+
+</section>
+
+
+<section id="njs_api_fs" name="File System">
+
+<para>
+The File System module provides operations with files.
+The module object is returned by <literal>require('fs')</literal>.
+<list type="tag">
+
+<tag-name id="appendfilesync"><literal>appendFileSync(<value>filename</value>,
+<value>data</value>[, <value>options</value>])</literal></tag-name>
+<tag-desc>
+Synchronously appends specified <literal>data</literal>
+to a file with provided <literal>filename</literal>.
+If the file does not exist, it will be created.
+The <literal>options</literal> parameter is expected to be
+an object with the following keys:
+<list type="tag">
+
+<tag-name><literal>mode</literal></tag-name>
+<tag-desc>
+mode option, by default is <literal>0o666</literal>
+</tag-desc>
+
+<tag-name><literal>flag</literal></tag-name>
+<tag-desc>
+file system <link id="njs_api_fs_flags">flag</link>,
+by default is <literal>a</literal>
+</tag-desc>
+
+</list>
+</tag-desc>
+
+<tag-name id="readfilesync"><literal>readFileSync(<value>filename</value>[,
+<value>options</value>])</literal></tag-name>
+<tag-desc>
+Synchronously returns the contents of the file
+with provided <literal>filename</literal>.
+The <literal>options</literal> parameter holds
+<literal>string</literal> that specifies encoding.
+If not specified, a <link id="string_tobytes">byte string</link> is returned.
+If <literal>utf8</literal> encoding is specified, a Unicode string is returned.
+Otherwise, <literal>options</literal> is expected to be
+an object with the following keys:
+<list type="tag">
+
+<tag-name><literal>encoding</literal></tag-name>
+<tag-desc>
+encoding, by default is not specified.
+The encoding can be <literal>utf8</literal>
+</tag-desc>
+
+<tag-name><literal>flag</literal></tag-name>
+<tag-desc>
+file system <link id="njs_api_fs_flags">flag</link>,
+by default is <literal>r</literal>
+</tag-desc>
+
+</list>
+<example>
+>> var fs = require('fs')
+undefined
+>> var file = fs.readFileSync('/file/path.tar.gz')
+undefined
+>> var gzipped = /^\x1f\x8b/.test(file); gzipped
+true
+</example>
+</tag-desc>
+
+<tag-name id="writefilesync"><literal>writeFileSync(<value>filename</value>,
+<value>data</value>[,
+<value>options</value>])</literal></tag-name>
+<tag-desc>
+Synchronously writes <literal>data</literal> to a file
+with provided <literal>filename</literal>.
+If the file does not exist, it will be created,
+if the file exists, it will be replaced.
+The <literal>options</literal> parameter is expected to be
+an object with the following keys:
+<list type="tag">
+<tag-name><literal>mode</literal></tag-name>
+<tag-desc>
+mode option, by default is <literal>0o666</literal>
+</tag-desc>
+
+<tag-name><literal>flag</literal></tag-name>
+<tag-desc>
+file system <link id="njs_api_fs_flags">flag</link>,
+by default is <literal>w</literal>
+</tag-desc>
+
+</list>
+<example>
+>> var fs = require('fs')
+undefined
+>> var file = fs.writeFileSync('hello.txt', 'Hello world')
+undefined
+</example>
+</tag-desc>
+
+</list>
+</para>
+
+
+<section id="njs_api_fs_flags" name="File System Flags">
+
+<para>
+The <literal>flag</literal> option can accept the following values:
+
+<list type= "bullet" compact="no">
+
+<listitem>
+<literal>a</literal>&mdash;open a file for appending.
+The file is created if it does not exist
+</listitem>
+
+<listitem>
+<literal>ax</literal>&mdash;the same as <literal>a</literal>
+but fails if the file already exists
+</listitem>
+
+<listitem>
+<literal>a+</literal>&mdash;open a file for reading and appending.
+If the file does not exist, it will be created
+</listitem>
+
+<listitem>
+<literal>ax+</literal>&mdash;the same as  <literal>a+</literal>
+but fails if the file already exists
+</listitem>
+
+<listitem>
+<literal>as</literal>&mdash;open a file for appending in synchronous mode.
+If the file does not exist, it will be created
+</listitem>
+
+<listitem>
+<literal>as+</literal>&mdash;open a file for reading and appending
+in synchronous mode.
+If the file does not exist, it will be created
+</listitem>
+
+<listitem>
+<literal>r</literal>&mdash;open a file for reading.
+An exception occurs if the file does not exist
+</listitem>
+
+<listitem>
+<literal>r+</literal>&mdash;open a file for reading and writing.
+An exception occurs if the file does not exist
+</listitem>
+
+<listitem>
+<literal>rs+</literal>&mdash;open a file for reading and writing
+in synchronous mode.
+Instructs the operating system to bypass the local file system cache
+</listitem>
+
+<listitem>
+<literal>w</literal>&mdash;open a file for writing.
+If the file does not exist, it will be created.
+If the file exists, it will be replaced
+</listitem>
+
+<listitem>
+<literal>wx</literal>&mdash;the same as <literal>w</literal>
+but fails if the file already exists
+</listitem>
+
+<listitem>
+<literal>w+</literal>&mdash;open a file for reading and writing.
+If the file does not exist, it will be created.
+If the file exists, it will be replaced
+</listitem>
+
+<listitem>
+<literal>wx+</literal>&mdash;the same as <literal>w+</literal>
+but fails if the file already exists
+</listitem>
+
+</list>
+</para>
+
+</section>
+
+</section>
+
+</section>
+
+
+<section id="http" name="HTTP Request">
+
+<para>
+The HTTP request object is available only in the
+<link doc="../http/ngx_http_js_module.xml">ngx_http_js_module</link> module.
+All string properties of the object are <link id="string">byte strings</link>.
+
+<list type="tag">
+
+<tag-name><literal>r.args{}</literal></tag-name>
+<tag-desc>
+request arguments object, read-only
+</tag-desc>
+
+<tag-name><literal>r.error(<value>string</value>)</literal></tag-name>
+<tag-desc>
+writes a <literal>string</literal> to the error log
+on the <literal>error</literal> level of logging
+</tag-desc>
+
+<tag-name><literal>r.finish()</literal></tag-name>
+<tag-desc>
+finishes sending a response to the client
+</tag-desc>
+
+<tag-name><literal>r.headersIn{}</literal></tag-name>
+<tag-desc>
+incoming headers object, read-only.
+<para>
+For example, the <literal>Foo</literal> header
+can be accessed with the syntax <literal>headersIn.foo</literal>
+or <literal>headersIn['Foo']</literal>
+</para>
+</tag-desc>
+
+<tag-name><literal>r.headersOut{}</literal></tag-name>
+<tag-desc>
+outgoing headers object, writable.
+<para>
+For example, the <literal>Foo</literal> header
+can be accessed with the syntax <literal>headersOut.foo</literal>
+or <literal>headersOut['Foo']</literal>
+</para>
+</tag-desc>
+
+<tag-name><literal>r.httpVersion</literal></tag-name>
+<tag-desc>
+HTTP version, read-only
+</tag-desc>
+
+<tag-name><literal>r.log(<value>string</value>)</literal></tag-name>
+<tag-desc>
+writes a <literal>string</literal> to the error log
+on the <literal>info</literal> level of logging
+</tag-desc>
+
+<tag-name id="r_internal_redirect"><literal>r.internalRedirect(<value>uri</value>)</literal></tag-name>
+<tag-desc>
+performs an internal redirect to the specified <literal>uri</literal>.
+If the uri starts with the “<literal>@</literal>” prefix,
+it is considered a named location.
+</tag-desc>
+
+<tag-name><literal>r.method</literal></tag-name>
+<tag-desc>
+HTTP method, read-only
+</tag-desc>
+
+<tag-name><literal>r.parent</literal></tag-name>
+<tag-desc>
+references the parent request object
+</tag-desc>
+
+<tag-name><literal>r.remoteAddress</literal></tag-name>
+<tag-desc>
+client address, read-only
+</tag-desc>
+
+<tag-name><literal>r.requestBody</literal></tag-name>
+<tag-desc>
+holds the request body, read-only
+</tag-desc>
+
+<tag-name><literal>r.responseBody</literal></tag-name>
+<tag-desc>
+holds the <link id="subrequest">subrequest</link> response body, read-only.
+The size of <literal>r.responseBody</literal> is limited by the
+<link doc="../http/ngx_http_core_module.xml" id="subrequest_output_buffer_size"/>
+directive.
+</tag-desc>
+
+<tag-name><literal>r.return(status[, string])</literal></tag-name>
+<tag-desc>
+sends the entire response
+with the specified <literal>status</literal> to the client
+<para>
+It is possible to specify either a redirect URL
+(for codes 301, 302, 303, 307, and 308)
+or the response body text (for other codes) as the second argument
+</para>
+</tag-desc>
+
+<tag-name><literal>r.send(<value>string</value>)</literal></tag-name>
+<tag-desc>
+sends a part of the response body to the client
+</tag-desc>
+
+<tag-name><literal>r.sendHeader()</literal></tag-name>
+<tag-desc>
+sends the HTTP headers to the client
+</tag-desc>
+
+<tag-name><literal>r.status</literal></tag-name>
+<tag-desc>
+status, writable
+</tag-desc>
+
+<tag-name><literal>r.variables{}</literal></tag-name>
+<tag-desc>
+nginx variables object, read-only
+</tag-desc>
+
+<tag-name><literal>r.warn(<value>string</value>)</literal></tag-name>
+<tag-desc>
+writes a <literal>string</literal> to the error log
+on the <literal>warning</literal> level of logging
+</tag-desc>
+
+<tag-name><literal>r.uri</literal></tag-name>
+<tag-desc>
+current URI, read-only
+</tag-desc>
+
+<tag-name id="subrequest"><literal>r.subrequest(<value>uri</value>[,
+<value>options</value>[, <value>callback</value>]])</literal></tag-name>
+<tag-desc>
+creates a subrequest with the given <literal>uri</literal> and
+<literal>options</literal>, and installs
+an optional completion <literal>callback</literal>.
+
+<para>
+If <literal>options</literal> is a string, then it
+holds the subrequest arguments string.
+Otherwise, <literal>options</literal> is expected to be
+an object with the following keys:
+<list type="tag">
+<tag-name><literal>args</literal></tag-name>
+<tag-desc>
+arguments string
+</tag-desc>
+<tag-name><literal>body</literal></tag-name>
+<tag-desc>
+request body
+</tag-desc>
+
+<tag-name><literal>method</literal></tag-name>
+<tag-desc>
+HTTP method
+</tag-desc>
+
+</list>
+</para>
+
+<para>
+The completion <literal>callback</literal> receives
+a subrequest response object with methods and properties
+identical to the parent request object.
+</para>
+</tag-desc>
+
+</list>
+</para>
+
+</section>
+
+
+<section id="stream" name="Stream Session">
+
+<para>
+The stream session object is available only in the
+<link doc="../stream/ngx_stream_js_module.xml">ngx_stream_js_module</link>
+module.
+All string properties of the object are <link id="string">byte strings</link>.
+</para>
+
+<para>
+<note>
+Prior to njs <link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>,
+the stream session object had some properties which are currently
+<link id="stream_obsolete">removed</link>.
+</note>
+</para>
+
+<para>
+<list type="tag">
+
+<tag-name id="s_allow"><literal>s.allow()</literal></tag-name>
+<tag-desc>
+successfully finalizes the phase handler
+(<link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>)
+</tag-desc>
+
+<tag-name id="s_decline"><literal>s.decline()</literal></tag-name>
+<tag-desc>
+finalizes the phase handler and passes control to the next handler
+(<link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>)
+</tag-desc>
+
+<tag-name id="s_deny"><literal>s.deny()</literal></tag-name>
+<tag-desc>
+finalizes the phase handler with the access error code
+(<link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>)
+</tag-desc>
+
+<tag-name id="s_done"><literal>s.done</literal>(<value>[code]</value>)</tag-name>
+<tag-desc>
+successfully finalizes the current phase handler
+or finalizes it with the specified numeric code
+(<link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>).
+</tag-desc>
+
+<tag-name><literal>s.error(<value>string</value>)</literal></tag-name>
+<tag-desc>
+writes a sent <literal>string</literal> to the error log
+on the <literal>error</literal> level of logging
+</tag-desc>
+
+<tag-name><literal>s.log(<value>string</value>)</literal></tag-name>
+<tag-desc>
+writes a sent <value>string</value> to the error log
+on the <literal>info</literal> level of logging
+</tag-desc>
+
+<tag-name id="s_off"><literal>s.off(<value>eventName</value>)</literal></tag-name>
+<tag-desc>
+unregisters the callback set by the <link id="s_on">s.on()</link> method
+(<link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>)
+</tag-desc>
+
+<tag-name id="s_on"><literal>s.on(<value>event</value>,
+<value>callback</value>)</literal></tag-name>
+<tag-desc>
+registers a <literal>callback</literal> for the specified <literal>event</literal>
+(<link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>).
+
+<para>
+An <literal>event</literal> may be one of the following strings:
+<list type="tag">
+<tag-name><literal>upload</literal></tag-name>
+<tag-desc>
+new data from a client
+</tag-desc>
+
+<tag-name><literal>download</literal></tag-name>
+<tag-desc>
+new data to a client
+</tag-desc>
+
+</list>
+</para>
+
+<para>
+The completion callback has the following prototype:
+<literal>callback(data, flags)</literal>, where
+<literal>data</literal> is string,
+<literal>flags</literal> is an object
+with the following properties:
+<list type="tag">
+<tag-name id="s_on_callback_last"><literal>last</literal></tag-name>
+<tag-desc>
+a boolean value, true if data is a last buffer.
+</tag-desc>
+
+</list>
+</para>
+</tag-desc>
+
+<tag-name><literal>s.remoteAddress</literal></tag-name>
+<tag-desc>
+client address, read-only
+</tag-desc>
+
+<tag-name id="s_send"><literal>s.send(<value>data</value>[,
+<value>options</value>])</literal></tag-name>
+<tag-desc>
+sends the data to the client
+(<link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>).
+The <literal>options</literal> is an object used
+to override nginx buffer flags derived from an incoming data chunk buffer.
+The flags can be overriden with the following flags:
+<para>
+<list type="tag">
+
+<tag-name><literal>last</literal></tag-name>
+<tag-desc>
+boolean, true if the buffer is the last buffer
+</tag-desc>
+
+<tag-name><literal>flush</literal></tag-name>
+<tag-desc>
+boolean, true if the buffer should have the <literal>flush</literal> flag
+</tag-desc>
+</list>
+</para>
+The method can be called multiple times per callback invocation.
+</tag-desc>
+
+<tag-name><literal>s.variables{}</literal></tag-name>
+<tag-desc>
+nginx variables object, read-only
+</tag-desc>
+
+<tag-name><literal>s.warn(<value>string</value>)</literal></tag-name>
+<tag-desc>
+writes a sent <literal>string</literal> to the error log
+on the <literal>warning</literal> level of logging
+</tag-desc>
+
+</list>
+</para>
+
+
+<section id="stream_obsolete" name="Obsolete properties">
+
+<para>
+These properties have been removed
+in njs <link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>
+and are not backward compatible with the existing njs code.
+</para>
+
+<para>
+<list type="tag">
+
+<tag-name id="s_abort"><literal>s.ABORT</literal></tag-name>
+<tag-desc>
+the <literal>ABORT</literal> return code
+<note>
+Starting from njs <link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>,
+the <link id="s_deny">s.deny()</link> method should be used instead.
+</note>
+</tag-desc>
+
+<tag-name><literal>s.AGAIN</literal></tag-name>
+<tag-desc>
+the <literal>AGAIN</literal> return code
+<note>
+Starting from njs <link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>,
+the corresponding behavior is achieved if no
+<link id="s_allow">s.allow()</link>,
+<link id="s_deny">s.deny()</link>,
+<link id="s_decline">s.decline()</link>,
+<link id="s_done">s.done()</link>
+is invoked and a callback is registered.
+</note>
+</tag-desc>
+
+<tag-name id="s_buffer"><literal>s.buffer</literal></tag-name>
+<tag-desc>
+the current buffer, writable
+<note>
+Starting from <link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>,
+the <link id="s_send">s.send()</link> method should be used for writing.
+For reading, the current buffer is available as the first argument of the
+<literal>event</literal> callback.
+</note>
+</tag-desc>
+
+<tag-name><literal>s.DECLINED</literal></tag-name>
+<tag-desc>
+the <literal>DECLINED</literal> return code
+<note>
+Starting from njs <link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>,
+the <link id="s_decline">s.decline()</link> method should be used instead.
+</note>
+</tag-desc>
+
+<tag-name><literal>s.eof</literal></tag-name>
+<tag-desc>
+a boolean read-only property, true if the current buffer is the last buffer
+<note>
+Starting from <link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>,
+the <link id="s_on_callback_last">flags.last</link> property
+should be used instead.
+</note>
+</tag-desc>
+
+<tag-name><literal>s.ERROR</literal></tag-name>
+<tag-desc>
+the <literal>ERROR</literal> return code
+<note>
+Starting from njs <link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>,
+an appropriate exception can be thrown to report an error.
+</note>
+</tag-desc>
+
+<tag-name><literal>s.fromUpstream</literal></tag-name>
+<tag-desc>
+a boolean read-only property,
+true if the current buffer is from the upstream server to the client
+<note>
+Starting from <link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>,
+a corresponding <link id="s_on">event</link>
+(<literal>upload</literal> or <literal>download</literal>)
+should be used to handle data to or from client.
+</note>
+</tag-desc>
+
+<tag-name id="s_ok"><literal>s.OK</literal></tag-name>
+<tag-desc>
+the <literal>OK</literal> return code
+<note>
+Starting from njs <link doc="../njs/changes.xml" id="njs0.2.4">0.2.4</link>,
+the <link id="s_allow">s.allow()</link> method should be used instead.
+</note>
+</tag-desc>
+
+</list>
+</para>
+
+</section>
+
+</section>
+
+
+</article>