激活的当前对象(buttom按钮)变色JS代码

实现点击过的扭按对象变色，在HTML文档写入下面代码：

<button>aa11</button>
<input type="button" value="aa22" /><button>aa33</button>
<input type="button" value="aa" /><button>aa</button>
<input type="button" value="aa" /><button>aa</button>
<input type="button" value="aa" />
<form style="border: solid 1px red"><button>aa</button>
<input type="BUTTON" value="aa" /><button>aa</button>
<input type="BUTTON" value="aa" /><button>aa</button>
<input type="BUTTON" value="aa" /></form><div>aaaaaaa<button>aa</button>
<input type="BUTTON" value="aa" />aaaaaaaaa</div>
<script>

window.onload = function Init(array)
{
    if(array == null)
    {
        Init(document.getElementsByTagName("INPUT"));
        Init(document.getElementsByTagName("BUTTON"));
        return;
    }
   
    if(!window.OnMouseOver) window.OnMouseOver = function()
    {
        if(this == window.currentButton) return;
        this.style.backgroundColor = "red";
        this.style['color']='#00ff00';
    }
    if(!window.OnMouseOut) window.OnMouseOut = function()
    {
        if(this == window.currentButton) return;
        this.style.backgroundColor = this.style.__backgroundColor;
    }
    if(!window.OnClick) window.OnClick = function()
    {
        if(window.currentButton) window.currentButton.style.backgroundColor = window.currentButton.style.__backgroundColor;
        this.style.backgroundColor = "blue";
        this.style['color']='#0000ff';
        window.currentButton = this;
       
    }
   
    var length = array.length;
    var btn;
    for(var i = 0; i < length; i++)
    {
        btn = array[i];
        if(btn.tagName != "BUTTON" && (btn.tagName != "INPUT" || btn.type != "button")) continue;
        btn.style.__backgroundColor = btn.style.backgroundColor;
        btn.onmouseover = window.OnMouseOver;
        btn.onmouseout = window.OnMouseOut;
        btn.onclick = window.OnClick;
    }

}

</script>