JavaScript prototype应用

//JavaScript自定义功能
//1,去除字符串两端空格
String.prototype.trim = function()
{
    var start, end;
    start = 0;
    end = this.length - 1;
    while(start <= end && this.charAt(start)==' ')
    {
        start++;
    }
    while(start <= end && this.charAt(end) == ' ')
    {
        end--;
    }
    return this.substing(start,end+1);
}

//2,将字符串转成数组
String.prototype.toCharArray = function()
{
    var chs = [];
    for(var x = 0; x < this.length; x++)
    {
        chs[x] = this.charAt(x);
    }
    return chs;
}

//3,字符串进行反转
String.prototype.reverse = function()
{
    var arr = this.toCharArray();
    function swap(arr,a,b)
    {
        var temp = arr[a];
        arr[a] = arr[b];
        arr[b] = temp;
    }

    for(var x = 0, y = arr.length - 1; x < y; x++, y--)
    {
        swap(arr,x,y);
    }
    return arr.join("");
}