Where to insert javascript code

In website development, JavaScript is a very important scripting language that can realize functions such as page interaction, dynamic effects, and data processing. So where should the JavaScript code be inserted? Let us find out below.

JavaScript code can be inserted at the head or end of the HTML document. Both positions have their own pros and cons and need to be decided based on specific needs.

Insert JavaScript code into the head

Inserting JavaScript code into the head of an HTML document is usually accomplished using the <script> tag. For example: </script>

nbsp;html>


    <title>JavaScript代码插入头部</title>
    <script></script>


    <h1 id="Hello-World">Hello World!</h1>

The above code means inserting a JavaScript code file named "example.js" into the HTML header. The advantage of placing JavaScript code in the head is that it can be loaded and executed immediately, but the disadvantage is that it blocks the loading of other elements of the page (such as images and text). Therefore, if the JavaScript code is long or complex, it is not appropriate to place it in the head.

Insert JavaScript code at the end

Inserting JavaScript code at the end of an HTML document is usually accomplished using the <script> tag. For example: </script>

nbsp;html>


    <title>JavaScript代码插入尾部</title>


    <h1 id="Hello-World">Hello World!</h1>
    <script></script>

The above code means inserting a JavaScript code file named "example.js" at the end of HTML. The advantage of placing the JavaScript code at the end is that other elements of the page can be loaded first, and there will be no lag or delay due to the loading of JavaScript. But the disadvantage is that the JavaScript code may need to wait until the entire page is loaded before it can be executed, so some users may need to wait for a while to see the corresponding effect.

Taking all things into consideration, in most cases, it is better to put JavaScript code at the end of the HTML document. However, in some specific cases, JavaScript code still needs to be placed in the head. For example, if you need to use some special libraries or frameworks, you may need to load the JS code in advance to meet the needs.

In addition, you can also use asynchronous loading to load JavaScript code, thereby avoiding blocking the entire page and improving loading speed and user experience. Commonly used methods include defer and async attributes, which can be used according to specific project needs.

In short, when choosing where to insert JavaScript code, it needs to be decided based on specific needs and project conditions to achieve optimal results.

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