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Full list of changes is at https://jekyllrb.com/docs/upgrading/2-to-3/. The tl;dr of it is: - Relative permalinks were removed, so all the files in the `docs` subdirectory need their permalink to be prefixed with `docs/` - `post` and `page` types were renamed to `posts` and `pages` respectively - `jekyll-paginate`, `pygments` and `redcarpet` are all now optional, so I needed to explicitly add it to the Gemfile. Jekyll now uses `rouge` rather than `pygments` for syntax highlighting, but rouge does not support highlighting individual lines (`hl_lines`) so we need to continue using Pygments. - Layout metadata (eg. `sectionid`) is now on a `layout` variable rather than `page` Tested the following pages and confirmed that they all work: - "Docs" link (getting started page): http://127.0.0.1:4000/react/docs/getting-started.html - Downloads: http://127.0.0.1:4000/react/downloads.html - Tutorial: http://127.0.0.1:4000/react/docs/tutorial.html - A few pages under the "docs" subdirectory, to confirm they're working properly: - http://127.0.0.1:4000/react/docs/addons.html - http://127.0.0.1:4000/react/docs/why-react.html - http://127.0.0.1:4000/react/docs/create-fragment.html - A few tips: - http://127.0.0.1:4000/react/tips/false-in-jsx.html - http://127.0.0.1:4000/react/tips/style-props-value-px.html - Non-English versions of the page: - http://127.0.0.1:4000/react/docs/getting-started-it-IT.html - http://127.0.0.1:4000/react/docs/getting-started-ja-JP.html
23 lines
816 B
Markdown
23 lines
816 B
Markdown
---
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id: controlled-input-null-value
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title: Value of null for Controlled Input
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layout: tips
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permalink: tips/controlled-input-null-value.html
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prev: children-props-type.html
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next: componentWillReceiveProps-not-triggered-after-mounting.html
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---
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Specifying the `value` prop on a [controlled component](/react/docs/forms.html) prevents the user from changing the input unless you desire so.
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You might have run into a problem where `value` is specified, but the input can still be changed without consent. In this case, you might have accidentally set `value` to `undefined` or `null`.
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The snippet below shows this phenomenon; after a second, the text becomes editable.
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```js
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ReactDOM.render(<input value="hi" />, mountNode);
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setTimeout(function() {
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ReactDOM.render(<input value={null} />, mountNode);
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}, 1000);
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```
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