How do I insert an element before everything else on a document?

2023-03-29 22:16 问答作者：

I don't think I can use insertBefore() because I do not know what element will be first in the DOM.

I am开发者_如何学运维 trying to insert a body tag (i.e. <body>).

Without using a library, try this:

document.body.insertBefore(document.createElement("div"), document.body.firstChild);

Well, but you can always check this:

If document body has at least one child, use document.body.insertBefore([the new element], document.body.firstChild)
If document body has no children, just use document.body.appendChild([the new element]).

The first element in the document will be document.body.children[0].

Use prepend() to add an element to the beginning of a container (the body). http://api.jquery.com/prepend/

$('body').prepend()

Use .insertBefore() method

document.body.insertBefore(newNode, document.body.children[0])

document.body.innerHTML = '<body>'+document.body.innerHTML+'</body>';

There. Simply envelops the current HTML with the body tag.

继续阅读：dom javascript

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