How to override the original method to implement rewrite

<html&gt;
&lt;head&gt;
&lt;meta http-equiv="Content-Type" content="text/html; charset=gb2312" /&gt;
&lt;script&gt;
function myblur () {
alert("1. Leave");
}
function bindEvent(func){
myblur = func;
}
function myonclick() {
bindEvent(function(){
alert("Oh my God! The myblur method is covered!");
});
}
&lt;/script&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;input type="text" onblur="myblur()" value="Select the cursor and then leave the cursor and call itmyblur()method"/&gt;
&lt;input type="button" onclick="myonclick()" value="covermyblur()" /&gt;
Note：covermyblur()back，再次光标选中输入框然back再离开
&lt;/body&gt;
&lt;/html&gt;