25 lines
1006 B
Markdown
25 lines
1006 B
Markdown
---
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title: prefix
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tags: browser,intermediate
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---
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Returns the prefixed version (if necessary) of a CSS property that the browser supports.
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- Use `Array.prototype.findIndex()` on an array of vendor prefix strings to test if `document.body` has one of them defined in its `CSSStyleDeclaration` object, otherwise return `null`.
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- Use `String.prototype.charAt()` and `String.prototype.toUpperCase()` to capitalize the property, which will be appended to the vendor prefix string.
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```js
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const prefix = prop => {
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const capitalizedProp = prop.charAt(0).toUpperCase() + prop.slice(1);
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const prefixes = ['', 'webkit', 'moz', 'ms', 'o'];
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const i = prefixes.findIndex(
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prefix => typeof document.body.style[prefix ? prefix + capitalizedProp : prop] !== 'undefined'
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);
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return i !== -1 ? (i === 0 ? prop : prefixes[i] + capitalizedProp) : null;
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};
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```
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```js
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prefix('appearance'); // 'appearance' on a supported browser, otherwise 'webkitAppearance', 'mozAppearance', 'msAppearance' or 'oAppearance'
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```
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