When the page opens, we need to perform some operations. At this time, if we choose to use jquery, we need to rewrite its 3 methods

No, it’s up to you. The second feeling is simple:

The first:

<script type="text/javascript" src="./js/jquery-1.7.min.js"></script>

<script type="text/javascript">
//init method one
$(document).ready(function(){
trace(" The initialization method enters ");
});
function trace(obj){
console.log(obj);
}
</script>

Firefox press f12 to debug why use console.log instead of alert! This everybody should be clearer!   The second:

<script type="text/javascript">
//init method one
$(function(){
trace(" The initialization method enters two ");
});
function trace(obj){
console.log(obj);
}
</script>

  The third:

<script type="text/javascript" src="./js/jquery-1.7.min.js"></script>
<script type="text/javascript">
//init method one
jQuery(function($){
trace(" The initialization method enters three ");
});
function trace(obj){
console.log(obj);
}
</script>

  Ps. Instead of using jquery to initialize a page,

1. Inside the body, “onload”

2. Write it in a script

window.onload=function(){
//Something to initialize
}