doc: general improvements to querystring.md copy

PR-URL: https://github.com/nodejs/node/pull/7023
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>

doc/api/querystring.md

@@ -4,58 +4,94 @@
 
 <!--name=querystring-->
 
-This module provides utilities for dealing with query strings.
-It provides the following methods:
+The `querystring` module provides utilities for parsing and formatting URL
+query strings. It can be accessed using:
 
-## querystring.escape
+```js
+const querystring = require('querystring');
+```
+
+## querystring.escape(str)
 <!-- YAML
 added: v0.1.25
 -->
 
-The escape function used by `querystring.stringify`,
-provided so that it could be overridden if necessary.
+* `str` {String}
+
+The `querystring.escape()` method performs URL percent-encoding on the given
+`str` in a manner that is optimized for the specific requirements of URL
+query strings.
 
-## querystring.parse(str[, sep][, eq][, options])
+The `querystring.escape()` method is used by `querystring.stringify()` and is
+generally not expected to be used directly. It is exported primarily to allow
+application code to provide a replacement percent-encoding implementation if
+necessary by assigning `querystring.escape` to an alternative function.
+
+## querystring.parse(str[, sep[, eq[, options]]])
 <!-- YAML
 added: v0.1.25
 -->
 
-Deserialize a query string to an object.
-Optionally override the default separator (`'&'`) and assignment (`'='`)
-characters.
+* `str` {String} The URL query string to parse
+* `sep` {String} The substring used to delimit key and value pairs in the
+  query string. Defaults to `'&'`.
+* `eq` {String}. The substring used to delimit keys and values in the
+  query string. Defaults to `'='`.
+* `options` {Object}
+  * `decodeURIComponent` {Function} The function to use when decoding
+    percent-encoded characters in the query string. Defaults to
+    `querystring.unescape()`.
+  * `maxKeys` {number} Specifies the maximum number of keys to parse.
+    Defaults to `1000`. Specify `0` to remove key counting limitations.
+
+The `querystring.parse()` method parses a URL query string (`str`) into a
+collection of key and value pairs.
 
-Options object may contain `maxKeys` property (equal to 1000 by default), it'll
-be used to limit processed keys. Set it to 0 to remove key count limitation.
+For example, the query string `'foo=bar&abc=xyz&abc=123'` is parsed into:
 
-Options object may contain `decodeURIComponent` property (`querystring.unescape` by default),
-it can be used to decode a `non-utf8` encoding string if necessary.
+```js
+{
+  foo: 'bar',
+  abc: ['xyz', '123']
+}
+```
 
-Example:
+*Note*: The object returned by the `querystring.parse()` method _does not_
+prototypically extend from the JavaScript `Object`. This means that the
+typical `Object` methods such as `obj.toString()`, `obj.hashOwnProperty()`,
+and others are not defined and *will not work*.
+
+By default, percent-encoded characters within the query string will be assumed
+to use UTF-8 encoding. If an alternative character encoding is used, then an
+alternative `decodeURIComponent` option will need to be specified as illustrated
+in the following example:
 
 ```js
-querystring.parse('foo=bar&baz=qux&baz=quux&corge')
-// returns { foo: 'bar', baz: ['qux', 'quux'], corge: '' }
+// Assuming gbkDecodeURIComponent function already exists...
 
-// Suppose gbkDecodeURIComponent function already exists,
-// it can decode `gbk` encoding string
 querystring.parse('w=%D6%D0%CE%C4&foo=bar', null, null,
   { decodeURIComponent: gbkDecodeURIComponent })
-// returns { w: '中文', foo: 'bar' }
 ```
 
-## querystring.stringify(obj[, sep][, eq][, options])
+## querystring.stringify(obj[, sep[, eq[, options]]])
 <!-- YAML
 added: v0.1.25
 -->
 
-Serialize an object to a query string.
-Optionally override the default separator (`'&'`) and assignment (`'='`)
-characters.
+* `obj` {Object} The object to serialize into a URL query string
+* `sep` {String} The substring used to delimit key and value pairs in the
+  query string. Defaults to `'&'`.
+* `eq` {String}. The substring used to delimit keys and values in the
+  query string. Defaults to `'='`.
+* `options`
+  * `encodeURIComponent` {Function} The function to use when converting
+    URL-unsafe characters to percent-encoding in the query string. Defaults to
+    `querystring.escape()`.
 
-Options object may contain `encodeURIComponent` property (`querystring.escape` by default),
-it can be used to encode string with `non-utf8` encoding if necessary.
+The `querystring.stringify()` method produces a URL query string from a
+given `obj` by iterating through the object's "own properties".
 
-Example:
+For example:
 
 ```js
 querystring.stringify({ foo: 'bar', baz: ['qux', 'quux'], corge: '' })
@@ -63,22 +99,35 @@ querystring.stringify({ foo: 'bar', baz: ['qux', 'quux'], corge: '' })
 
 querystring.stringify({foo: 'bar', baz: 'qux'}, ';', ':')
 // returns 'foo:bar;baz:qux'
+```
+
+By default, characters requiring percent-encoding within the query string will
+be encoded as UTF-8. If an alternative encoding is required, then an alternative
+`encodeURIComponent` option will need to be specified as illustrated in the
+following example:
+
+```js
+// Assuming gbkEncodeURIComponent function already exists,
 
-// Suppose gbkEncodeURIComponent function already exists,
-// it can encode string with `gbk` encoding
 querystring.stringify({ w: '中文', foo: 'bar' }, null, null,
   { encodeURIComponent: gbkEncodeURIComponent })
-// returns 'w=%D6%D0%CE%C4&foo=bar'
 ```
 
-## querystring.unescape
+## querystring.unescape(str)
 <!-- YAML
 added: v0.1.25
 -->
+* `str` {String}
+
+
+The `querystring.unescape()` method performs decoding of URL percent-encoded
+characters on the given `str`.
 
-The unescape function used by `querystring.parse`,
-provided so that it could be overridden if necessary.
+The `querystring.unescape()` method is used by `querystring.parse()` and is
+generally not expected to be used directly. It is exported primarily to allow
+application code to provide a replacement decoding implementation if
+necessary by assigning `querystring.unescape` to an alternative function.
 
-It will try to use `decodeURIComponent` in the first place,
-but if that fails it falls back to a safer equivalent that
-doesn't throw on malformed URLs.
+By default, the `querystring.unescape()` method will attempt to use the
+JavaScript built-in `decodeURIComponent()` method to decode. If that fails,
+a safer equivalent that does not throw on malformed URLs will be used.