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# CSS Blank Pseudo [<img src="http://jonathantneal.github.io/js-logo.svg" alt="" width="90" height="90" align="right">][CSS Blank Pseudo] |
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[![NPM Version][npm-img]][npm-url] |
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[<img alt="Discord" src="https://shields.io/badge/Discord-5865F2?logo=discord&logoColor=white">][discord] |
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[CSS Blank Pseudo] lets you style form elements when they are empty, following |
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the [Selectors Level 4] specification. |
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```css |
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input { |
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/* style an input */ |
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} |
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input:blank { |
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/* style an input without a value */ |
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} |
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``` |
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## Usage |
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From the command line, transform CSS files that use `:blank` selectors: |
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```bash |
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npx css-blank-pseudo SOURCE.css --output TRANSFORMED.css |
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``` |
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Next, use your transformed CSS with this script: |
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```html |
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<link rel="stylesheet" href="TRANSFORMED.css"> |
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<script src="https://unpkg.com/css-blank-pseudo/dist/browser-global.js"></script> |
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<script>cssBlankPseudo(document)</script> |
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``` |
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⚠️ Please use a versioned url, like this : `https://unpkg.com/css-blank-pseudo@3.0.0/dist/browser-global.js` |
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Without the version, you might unexpectedly get a new major version of the library with breaking changes. |
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⚠️ If you were using an older version via a CDN, please update the entire url. |
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The old URL will no longer work in a future release. |
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That’s it. The script works in most browsers. |
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## How it works |
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The [PostCSS plugin](README-POSTCSS.md) clones rules containing `:blank`, |
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replacing them with an alternative `[blank]` selector. |
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```css |
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input:blank { |
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background-color: yellow; |
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} |
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/* becomes */ |
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input[blank] { |
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background-color: yellow; |
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} |
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input:blank { |
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background-color: yellow; |
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} |
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``` |
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Next, the [JavaScript library](README-BROWSER.md) adds a `blank` attribute to |
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elements otherwise matching `:blank` natively. |
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```html |
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<input value="" blank> |
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<input value="This element has a value"> |
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``` |
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## ⚠️ `:not(:blank)` |
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with option : `preserve` `true` |
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```css |
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input:not(:blank) { |
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background-color: yellow; |
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} |
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/* becomes */ |
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input:not([blank]) { |
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background-color: yellow; |
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} |
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input:not(:blank) { |
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background-color: yellow; |
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} |
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``` |
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When you do not include the JS polyfill one will always match in browsers that support `:blank` natively. |
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In browsers that do not support `:blank` natively the rule will be invalid. |
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_currently no browsers support `:blank`_ |
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[discord]: https://discord.gg/bUadyRwkJS |
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[npm-img]: https://img.shields.io/npm/v/css-blank-pseudo.svg |
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[npm-url]: https://www.npmjs.com/package/css-blank-pseudo |
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[CSS Blank Pseudo]: https://github.com/csstools/postcss-plugins/tree/main/plugins/css-blank-pseudo |
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[PostCSS Preset Env]: https://preset-env.cssdb.org/ |
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[Selectors Level 4]: https://drafts.csswg.org/selectors-4/#blank
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