javascript获取难以索引的对象

1.Eval

function  simpleSwap()
{
    var the_image = prompt("change parrot or cheese","");
    var the_image_name = "window.document." + the_image;
    var the_image_object = eval(the_image_name);
    the_image_object.src = "ant.gif";
}

2.名称索引

function  simpleSwap()
{
    var the_image = prompt("change parrot or cheese","");
    window.document.images[the_image].src = "ant.gif";
}