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));