在String原型上去除字符串的空白符

        //左空格
        String.prototype.leftSpace = function(){
            return this.replace(/^\s+/g,"")
        }
        //右空格
        String.prototype.rightSpace = function(){
            return this.replace(/\s+$/g,"");
        }
        //全部空格
        String.prototype.allSpace = function(){
            return this.replace(/\s+/g,"");
        }
        //左右空格
        String.prototype.rlSpace = function(){
            return this.replace(/(^\s+)||(\s+$)/g,"")
        }
        var str = new String('    1   2  3  5  4     ');
        console.log(str.leftSpace());
        console.log(str.rightSpace());
        console.log(str.allSpace());
        console.log(str.rlSpace());