stringify.js

var cx = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
    escapable = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
    gap,
    indent,
    meta = {    // table of character substitutions
        '\b': '\\b',
        '\t': '\\t',
        '\n': '\\n',
        '\f': '\\f',
        '\r': '\\r',
        '"' : '\\"',
        '\\': '\\\\'
    },
    rep;

function quote(string) {
    // If the string contains no control characters, no quote characters, and no
    // backslash characters, then we can safely slap some quotes around it.
    // Otherwise we must also replace the offending characters with safe escape
    // sequences.
    
    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 + '"';
}

function str(key, holder) {
    // Produce a string from holder[key].
    var i,          // The loop counter.
        k,          // The member key.
        v,          // The member value.
        length,
        mind = gap,
        partial,
        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);
    }
    
    // If we were called with a replacer function, then call the replacer to
    // obtain a replacement value.
    if (typeof rep === 'function') {
        value = rep.call(holder, key, value);
    }
    
    // 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 (!value) return 'null';
            gap += indent;
            partial = [];
            
            // Array.isArray
            if (Object.prototype.toString.apply(value) === '[object Array]') {
                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;
            }
            
            // If the replacer is an array, use it to select the members to be
            // stringified.
            if (rep && typeof rep === 'object') {
                length = rep.length;
                for (i = 0; i < length; i += 1) {
                    k = rep[i];
                    if (typeof k === 'string') {
                        v = str(k, value);
                        if (v) {
                            partial.push(quote(k) + (gap ? ': ' : ':') + v);
                        }
                    }
                }
            }
            else {
                // Otherwise, iterate through all of the keys in the object.
                for (k in value) {
                    if (Object.prototype.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;
    }
}

module.exports = function (value, replacer, space) {
    var i;
    gap = '';
    indent = '';
    
    // If the space parameter is a number, make an indent string containing that
    // many spaces.
    if (typeof space === 'number') {
        for (i = 0; i < space; i += 1) {
            indent += ' ';
        }
    }
    // If the space parameter is a string, it will be used as the indent string.
    else if (typeof space === 'string') {
        indent = space;
    }

    // If there is a replacer, it must be a function or an array.
    // Otherwise, throw an error.
    rep = replacer;
    if (replacer && typeof replacer !== 'function'
    && (typeof replacer !== 'object' || typeof replacer.length !== 'number')) {
        throw new Error('JSON.stringify');
    }
    
    // Make a fake root object containing our value under the key of ''.
    // Return the result of stringifying the value.
    return str('', {'': value});
};