Mo
MutationObserver Playground
Web API
Dev Vault
Observer Config
childList
Watch added/removed child nodes
attributes
Watch attribute changes
characterData
Watch text content changes
subtree
Observe all descendants too
attributeOldValue
Record previous attribute value
characterDataOldValue
Record previous text value
Mutate the DOM
childList
Add child element
childList
Remove last child
childList
Reorder children
attributes
Add/toggle class
attributes
Set data-* attribute
attributes
Change style
characterData
Edit text content
childList
Replace all children
Observed DOM Tree
0 nodes
All modern browsers
MutationObserver — watch DOM changes without polling
Mutation Log
Code
Click actions on the left to trigger mutations