js将js数组或者对象转换成json字符串

今天有同事问我怎么讲js数组或者对象转换成json字符串，恰巧下班后有时间，然后就整理一下，前台怎么讲数组后者对象转换成json字符串。

jquery为我们提供了一个类库jquery.json-2.4.js。此类库里边封装了对js对象转换成json的方法。$.toJSON(value);这样就可以很简单的讲value转换成json字符串。

下边我就贴出此类库的源码:

/**
* jQuery JSON plugin 2.4.0
*
* @author Brantley Harris, 2009-2011
* @author Timo Tijhof, 2011-2012
* @source This plugin is heavily influenced by MochiKit's serializeJSON, which is
*         copyrighted 2005 by Bob Ippolito.
* @source Brantley Harris wrote this plugin. It is based somewhat on the JSON.org
*         website's http://www.json.org/json2.js, which proclaims:
*         "NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.", a sentiment that
*         I uphold.
* @license MIT License <http://www.opensource.org/licenses/mit-license.php>
*/
(function($) {
'use strict';

var escape = /["\\\x00-\x1f\x7f-\x9f]/g,
meta = {
'\b': '\\b',
'\t': '\\t',
'\n': '\\n',
'\f': '\\f',
'\r': '\\r',
'"': '\\"',
'\\': '\\\\'
},
hasOwn = Object.prototype.hasOwnProperty;

/**
* jQuery.toJSON
* Converts the given argument into a JSON representation.
*
* @param o {Mixed} The json-serializable *thing* to be converted
*
* If an object has a toJSON prototype, that will be used to get the representation.
* Non-integer/string keys are skipped in the object, as are keys that point to a
* function.
*
*/
$.toJSON = typeof JSON === 'object' && JSON.stringify ? JSON.stringify : function(o) {
if (o === null) {
return 'null';
}

var pairs, k, name, val,
type = $.type(o);

if (type === 'undefined') {
return undefined;
}

// Also covers instantiated Number and Boolean objects,
// which are typeof 'object' but thanks to $.type, we
// catch them here. I don't know whether it is right
// or wrong that instantiated primitives are not
// exported to JSON as an {"object":..}.
// We choose this path because that's what the browsers did.
if (type === 'number' || type === 'boolean') {
return String(o);
}
if (type === 'string') {
return $.quoteString(o);
}
if (typeof o.toJSON === 'function') {
return $.toJSON(o.toJSON());
}
if (type === 'date') {
var month = o.getUTCMonth() + 1,
day = o.getUTCDate(),
year = o.getUTCFullYear(),
hours = o.getUTCHours(),
minutes = o.getUTCMinutes(),
seconds = o.getUTCSeconds(),
milli = o.getUTCMilliseconds();

if (month < 10) {
month = '0' + month;
}
if (day < 10) {
day = '0' + day;
}
if (hours < 10) {
hours = '0' + hours;
}
if (minutes < 10) {
minutes = '0' + minutes;
}
if (seconds < 10) {
seconds = '0' + seconds;
}
if (milli < 100) {
milli = '0' + milli;
}
if (milli < 10) {
milli = '0' + milli;
}
return '"' + year + '-' + month + '-' + day + 'T' +
hours + ':' + minutes + ':' + seconds +
'.' + milli + 'Z"';
}

pairs = [];

if ($.isArray(o)) {
for (k = 0; k < o.length; k++) {
pairs.push($.toJSON(o[k]) || 'null');
}
return '[' + pairs.join(',') + ']';
}

// Any other object (plain object, RegExp, ..)
// Need to do typeof instead of $.type, because we also
// want to catch non-plain objects.
if (typeof o === 'object') {
for (k in o) {
// Only include own properties,
// Filter out inherited prototypes
if (hasOwn.call(o, k)) {
// Keys must be numerical or string. Skip others
type = typeof k;
if (type === 'number') {
name = '"' + k + '"';
} else if (type === 'string') {
name = $.quoteString(k);
} else {
continue;
}
type = typeof o[k];

// Invalid values like these return undefined
// from toJSON, however those object members
// shouldn't be included in the JSON string at all.
if (type !== 'function' && type !== 'undefined') {
val = $.toJSON(o[k]);
pairs.push(name + ':' + val);
}
}
}
return '{' + pairs.join(',') + '}';
}
};

/**
* jQuery.evalJSON
* Evaluates a given json string.
*
* @param str {String}
*/
$.evalJSON = typeof JSON === 'object' && JSON.parse ? JSON.parse : function(str) {
/*jshint evil: true */
return eval('(' + str + ')');
};

/**
* jQuery.secureEvalJSON
* Evals JSON in a way that is *more* secure.
*
* @param str {String}
*/
$.secureEvalJSON = typeof JSON === 'object' && JSON.parse ? JSON.parse : function(str) {
var filtered =
str
.replace(/\\["\\\/bfnrtu]/g, '@')
.replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, ']')
.replace(/(?:^|:|,)(?:\s*\[)+/g, '');

if (/^[\],:{}\s]*$/.test(filtered)) {
/*jshint evil: true */
return eval('(' + str + ')');
}
throw new SyntaxError('Error parsing JSON, source is not valid.');
};

/**
* jQuery.quoteString
* Returns a string-repr of a string, escaping quotes intelligently.
* Mostly a support function for toJSON.
* Examples:
* >>> jQuery.quoteString('apple')
* "apple"
*
* >>> jQuery.quoteString('"Where are we going?", she asked.')
* "\"Where are we going?\", she asked."
*/
$.quoteString = function(str) {
if (str.match(escape)) {
return '"' + str.replace(escape, function(a) {
var c = meta[a];
if (typeof c === 'string') {
return c;
}
c = a.charCodeAt();
return '\\u00' + Math.floor(c / 16).toString(16) + (c % 16).toString(16);
}) + '"';
}
return '"' + str + '"';
};

}(jQuery));