Some questions and answers on the use of document.write in js_javascript skills

I am a newbie, so I recorded it. This answer was seen on Baidu, so it is considered a reprint.

The following content explains why if document.write is called after the page is loaded, the entire document will be overwritten.

The [HTML output] in the prompt refers to when the page is loaded.

Copy code The code is as follows:

< ;/head>

When the page is loaded, you will see Hello on the page. View the source file which is the code above.

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But if the page has been loaded, use document.write again, That will cover the entire document.

Copy code The code is as follows:

< ;/head>

Because the mouse action is executed after the page is loaded, the entire page will be covered by Javascript. Viewing the source file now will only see Javascript.