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30-seconds-of-code/snippets/observeMutations.md
2018-01-13 14:58:52 +02:00

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### observeMutations
Runs the provided callback for each mutation on the specified element.
Use a [`MutationObserver`](https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver) to observe mutations on the given element.
Use `Array.forEach()` to run the callback for each mutation that is observed.
Omit the third argument, `options`, to use the default [options](https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver#MutationObserverInit) (all `true`).
```js
const observeMutations = (element, callback, options) => new MutationObserver(mutations => mutations.forEach(m => callback(m))).observe(element, Object.assign(
{
childList: true,
attributes: true,
attributeOldValue: true,
characterData: true,
characterDataOldValue: true,
subtree: true
}, options));
```
```js
observeMutations(document, console.log); // Logs all mutations that happen on the page
```