Replacing all children of an HTMLElement?

Question

In my code, I fairly frequently need to replace all children of a certain HTML container with a new list of children.

What is the fastest way to do this? My current approach is collecting all new elements into a DocumentFragment. The only way I've found to then actually replace the children is to remove all the children one by one, and append the fragment. Is there no faster way?

Note: the solution needs not be cross-browser, but should preferably not require 3d-party components such as jQuery. The target-device is WebKit on a very slow CPU so I need to keep full control of any reflows.

Answer 1

If you simply want to replace all children, regarding of the type, why don't you just set its content to '' and then add your code:

container.innerHTML = ''; container.appendChild( newContainerElements ); 

that would basically remove all the children in the fastest possible way :)

Answer 2

2020 Update - use the replaceChildren() API!

Replacing all children can now be done with the (cross-browser supported) replaceChildren() API:

container.replaceChildren(...arrayOfNewChildren); 

This will do both: a) remove all existing children, and b) append all of the given new children, in one operation.

You can also use this same API to just remove existing children, without replacing them:

container.replaceChildren(); 

This is supported in Chrome/Edge 86+, Firefox 78+, and Safari 14+. It is fully specified behavior. This is likely to be faster than any other proposed method here, since the removal of old children and addition of new children is done a) without requiring innerHTML, and b) in one step instead of multiple.