jsRegExp.trim.js - implement the trim function of string with both regExp and string functions, while string functions has poor performance.

jsRegExp.trim.js

String.prototype.trim = function () {
    var reg = /^\s+|\s+$/g,
        tr = function (full, hs, content, es) {
            alert('full: ' + full + '; hs: ' + hs + '; content: ' + content + '; es: ' + es);
            return content;
        };
    return this.replace(reg, '');
};

//trim with string functions, with very poor performance.
function trim(str) {
    var str = str.replace(/^\s\s*/, ''),
        ws = /\s/,
        i = str.length;
    while (ws.test(str.charAt(--i)));
    return str.slice(0, i + 1);
}

var case1 = " xx x_  ";
var res = case1.trim();
console.log('res.length: ' + res.length + '; res: ' + res);