Javascript json_encode : JSON : PHP functions in JavaScript JAVASCRIPT TUTORIALS

function json_encode(mixed_val) {
    // Returns the JSON representation of a value  
    // 
    // version: 901.2515
    // discuss at: http://phpjs.org/functions/json_encode
    // +      original by: Public Domain (http://www.json.org/json2.js)
    // + reimplemented by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // *     example 1: json_encode(['e', {pluribus: 'unum'}]);
    // *     returns 1: '[\n    "e",\n    {\n    "pluribus": "unum"\n}\n]'
    /*
        http://www.JSON.org/json2.js
        2008-11-19
        Public Domain.
        NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
        See http://www.JSON.org/js.html
    */
    
    var indent;
    var value = mixed_val;
    var i;

    var quote = function (string) {
        var escapable = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;
        var meta = {    // table of character substitutions
            '\b': '\\b',
            '\t': '\\t',
            '\n': '\\n',
            '\f': '\\f',
            '\r': '\\r',
            '"' : '\\"',
            '\\': '\\\\'
        };

        escapable.lastIndex = 0;
        return escapable.test(string) ?
        '"' + string.replace(escapable, function (a) {
            var c = meta[a];
            return typeof c === 'string' ? c :
            '\\u' + ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
        }) + '"' :
        '"' + string + '"';
    }

    var str = function(key, holder) {
        var gap = '';
        var indent = '    ';
        var i = 0;          // The loop counter.
        var k = '';          // The member key.
        var v = '';          // The member value.
        var length = 0;
        var mind = gap;
        var partial = [];
        var value = holder[key];

        // If the value has a toJSON method, call it to obtain a replacement value.
        if (value && typeof value === 'object' &&
            typeof value.toJSON === 'function') {
            value = value.toJSON(key);
        }
        
        // What happens next depends on the value's type.
        switch (typeof value) {
            case 'string':
                return quote(value);

            case 'number':
                // JSON numbers must be finite. Encode non-finite numbers as null.
                return isFinite(value) ? String(value) : 'null';

            case 'boolean':
            case 'null':
                // If the value is a boolean or null, convert it to a string. Note:
                // typeof null does not produce 'null'. The case is included here in
                // the remote chance that this gets fixed someday.

                return String(value);

            case 'object':
                // If the type is 'object', we might be dealing with an object or an array or
                // null.
                // Due to a specification blunder in ECMAScript, typeof null is 'object',
                // so watch out for that case.
                if (!value) {
                    return 'null';
                }

                // Make an array to hold the partial results of stringifying this object value.
                gap += indent;
                partial = [];

                // Is the value an array?
                if (Object.prototype.toString.apply(value) === '[object Array]') {
                    // The value is an array. Stringify every element. Use null as a placeholder
                    // for non-JSON values.

                    length = value.length;
                    for (i = 0; i < length; i += 1) {
                        partial[i] = str(i, value) || 'null';
                    }

                    // Join all of the elements together, separated with commas, and wrap them in
                    // brackets.
                    v = partial.length === 0 ? '[]' :
                    gap ? '[\n' + gap +
                    partial.join(',\n' + gap) + '\n' +
                    mind + ']' :
                    '[' + partial.join(',') + ']';
                    gap = mind;
                    return v;
                }

                // Iterate through all of the keys in the object.
                for (k in value) {
                    if (Object.hasOwnProperty.call(value, k)) {
                        v = str(k, value);
                        if (v) {
                            partial.push(quote(k) + (gap ? ': ' : ':') + v);
                        }
                    }
                }

                // Join all of the member texts together, separated with commas,
                // and wrap them in braces.
                v = partial.length === 0 ? '{}' :
                gap ? '{\n' + gap + partial.join(',\n' + gap) + '\n' +
                mind + '}' : '{' + partial.join(',') + '}';
                gap = mind;
                return v;
        }
    };

    // Make a fake root object containing our value under the key of ''.
    // Return the result of stringifying the value.
    return str('', {
        '': value
    });
}