Which tag can embed javascript directly?

Which tag can be directly embedded in JavaScript: Detailed explanation of script tag

When writing web pages, we often need to use JavaScript to achieve some interactive effects, and using JavaScript in HTML requires the use of script tags. So which tag can embed JavaScript directly? The answer is script tags. In this article, we will explain the script tag in detail.

1. What is a script tag?

The script tag is an important tag in the HTML language. Its main function is to quote or embed JavaScript code. When using script tags, we can reference external JavaScript files through the src attribute, or embed JavaScript code inside the tag.

2. Attributes of the script tag

When using the script tag, we can use the following attributes to specify the JavaScript code source:

1. src attribute: used to specify The URL address of the external JavaScript file.
2. type attribute: used to specify the MIME type of the script language, the default is text/javascript.
3. async attribute: used to specify asynchronous loading of the page, only applicable to external JavaScript files.
4. defer attribute: used to specify page delay loading, only applicable to external JavaScript files.
5. charset attribute: used to specify the character set of JavaScript files.

3. The location of the script tag

In an HTML page, the script tag can be placed in the tag or in the tag. When placed in the tag, the JavaScript code will be loaded and executed when the page is loaded, which will extend the loading time of the page; when placed in the tag, the page will be loaded first, and then Execute JavaScript code.

4. Usage of script tag

1. Introducing external JavaScript files

We can use the src attribute to introduce external JavaScript files:

2. Embedded JavaScript code

We can also embed JavaScript code into the script tag Internal:

<script><br> document.write("Hello, world!");<br></script>

3. Use type attribute

When using the script tag, we can use the type attribute to specify the MIME type of the script language:

In HTML5, we can omit the type attribute because the default value of this attribute is text/javascript.

4. Use async attributes

Using async attributes can make the page load faster, but the order of asynchronously loaded JavaScript code is not guaranteed when executed:

5. Use the defer attribute

Use the defer attribute to load the page first, and then Execute JavaScript code:

Note that the defer attribute only applies to external JavaScript files, not to embedded code .

5. Frequently Asked Questions and Solutions

1. Why can’t the script tag be placed at the end of the tag?

Because JavaScript code will block the loading of the page, if placed at the end of the tag, it will cause the page to have a white screen for a long time, affecting the user experience. It is recommended to place the script tag in the tag, or use asynchronous loading or delayed loading.

2. Why is it recommended to place the script tag at the end of the tag?

Because placing it at the end of the tag allows the page to be loaded first, improving user experience. If the script tag is placed at the head of the tag, it will cause the page to be blank for a long time, affecting the user experience.

3. Why does using the defer attribute not guarantee the execution order of JavaScript code?

Because the execution order of JavaScript files with multiple defer attributes is determined by the order in which they appear in the page, and the order of JavaScript files in the page is uncertain. Therefore, pay attention to the dependencies between codes when using the defer attribute to avoid errors.

When using JavaScript, the script tag is indispensable. Through the explanation in this article, I believe that readers have mastered the usage of script tags, and I hope it will be helpful to readers when writing web pages.

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