JavaScript code placement location for javascript program development, JavaScript Program Development

JavaScript code placement location for javascript program development, JavaScript Program Development

When JavaScript is used on pages, where should these JS Code be placed? Let's take a look.

Generally, there are two ways to write on the interface and use. js files.

1.1 Head part on the Interface

You can directly put it in the head label, as shown in the following code:

1.2 body section on the Interface
Generally, it is directly placed in the body, as shown below:
There is no difference between head and body. Generally, when there is not much code, and only the current page uses these js, you can directly write it on the interface.
2. JS files
For JavaScript code that is complex and has a large amount of code, it is best to put it in a special. JS file and reference it on the page according to the relative path of the js file.
The advantage is that it can prevent a lot of duplicate js Code. Some common js methods can be put in external js files.
For example, general use visual studio 2010 New asp.net project with jquery-1.4.1.js files, we see how to use this js file.
For example, the file structure of the page,


You need to use this js file in MyJSFrm. aspx to introduce it like this.
In short, do not forget to use the relative directory. If the directory level of the current page file is relatively deep, use ../to calculate the directory level by yourself.
Differences between three js locations:
Head:
-- The script has been loaded when it is called.
--
Body:
-- The page is loaded when the page is generated.
--
External js:
-- Reference external js Note: External js cannot contain the <script> </script> labels
-- This mainly aims to save the cost of embedding the same js Code in each page when multiple pages call the same js function repeatedly;
The browser does not recognize js. Solution: <! --
Code Section
// -->
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