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Explicitly note that ref callbacks are called before componentDidMount. #216

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Oct 30, 2017
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Explicitly note that ref callbacks are called before componentDidMount. #216

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Explicitly note that ref callbacks are called before `componentDidMou…
knpwrs Oct 27, 2017
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Note that ref callbacks can update during render and be called after …
knpwrs Oct 28, 2017
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2 changes: 1 addition & 1 deletion content/docs/refs-and-the-dom.md
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Expand Up @@ -66,7 +66,7 @@ class CustomTextInput extends React.Component {
}
```

React will call the `ref` callback with the DOM element when the component mounts, and call it with `null` when it unmounts.
React will call the `ref` callback with the DOM element when the component mounts, and call it with `null` when it unmounts. `ref` callbacks will be called before `componentDidMount`.
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@bvaughn bvaughn Oct 28, 2017 •
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This new wording could be slightly confusing because ref callbacks might be called after mount if a new ref callback is provided (as is the case with arrow-functions that are recreated each time render is run). In that case, React clears the old one and calls the new one during the render phase (before componentDidMount / componentDidUpdate).

Edit: The caveat I mentioned above is mentioned later on the same docs page.

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@bvaughn bvaughn Oct 28, 2017 •
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Guh, GitHub keeps auto-submitting my comment on Enter when I don't intend it. Sorry.

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What do you think of wording more like:

ref callbacks are invoked before componentDidMount or componentDidUpdate lifecycle hooks.

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Sounds good to me, I'll push an update.


Using the `ref` callback just to set a property on the class is a common pattern for accessing DOM elements. The preferred way is to set the property in the `ref` callback like in the above example. There is even a shorter way to write it: `ref={input => this.textInput = input}`.

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