闭包1-2

by xiaoji121

HTML

<button>0</button> 
<button>1</button> 
<button>2</button> 
<button>3</button>

JavaScript

var button = document.getElementsByTagName("button");
// 改良后
var addEventListener = function(nodes){
    var helper = function(i){
        return function(e){
            alert(i);
        };
    };

    var i;

    for(i = 0; i < nodes.length; i++){
        nodes[i].onclick = helper(i);
    }
}

addEventListener(button);