Array toString

Array.prototype.toString = function() {
    return (function formatValue(x) {
        if (typeof x == "string") {
            return "'" + x.replace(/\n/g,"\\n") + "'";
        }
        if (typeof x == "number" && x === 0 && (1/x === -Infinity)) {
            return "-0";
        }
        if (Array.isArray(x)) {
            return "[" + x.map(formatValue).join(",") + "]";
        }
        if (x !== null && typeof x == "object") {
            return "{" + Object.keys(x).reduce(function(r,k){
                if (k != "toString" && k != "valueOf") {
                    r.push("'" + k + "':" + formatValue(x[k]));
                }
                return r;
            },[]).join(",") + "}";
        }
        return String(x);
    })(this);
};