JavaScript add onclick event to form

Both javaScript and JQuery, have problems in redefining some attributes directly in form.
Such as type='text', we could not remodify the type. So does the attribute onclick.


Method one：（Isolated button onclick event）：

var button = document.getElementById("yourbuttonId");
button.onclick = function(){alert('aaaaaaaa');};

Note: this method could used in any web browser
(注：此方法适用于任何浏览器。不存在兼容问题。推荐～～)

Method two:（the submit event in form）

var form = document.getElementById("yourformId");
form.onsubmit = function(){alert('aaaaa');};
form.action = "javascript:void(0)";

Note: javascript:void(0) makes the form do noting in action