51 lines
2.0 KiB
Markdown
51 lines
2.0 KiB
Markdown
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# abab [](https://www.npmjs.com/package/abab) [](https://travis-ci.org/jsdom/abab)
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A JavaScript module that implements `window.atob` and `window.btoa` according the forgiving-base64 algorithm in the [Infra Standard](https://infra.spec.whatwg.org/#forgiving-base64). The original code was forked from [w3c/web-platform-tests](https://github.com/w3c/web-platform-tests/blob/master/html/webappapis/atob/base64.html).
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Compatibility: Node.js version 3+ and all major browsers.
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Install with `npm`:
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```sh
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npm install abab
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```
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## API
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### `btoa` (base64 encode)
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```js
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const { btoa } = require('abab');
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btoa('Hello, world!'); // 'SGVsbG8sIHdvcmxkIQ=='
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```
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### `atob` (base64 decode)
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```js
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const { atob } = require('abab');
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atob('SGVsbG8sIHdvcmxkIQ=='); // 'Hello, world!'
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```
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#### Valid characters
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[Per the spec](https://html.spec.whatwg.org/multipage/webappapis.html#atob:dom-windowbase64-btoa-3), `btoa` will accept strings "containing only characters in the range `U+0000` to `U+00FF`." If passed a string with characters above `U+00FF`, `btoa` will return `null`. If `atob` is passed a string that is not base64-valid, it will also return `null`. In both cases when `null` is returned, the spec calls for throwing a `DOMException` of type `InvalidCharacterError`.
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## Browsers
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If you want to include just one of the methods to save bytes in your client-side code, you can `require` the desired module directly.
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```js
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const atob = require('abab/lib/atob');
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const btoa = require('abab/lib/btoa');
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```
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-----
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### Checklists
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If you're **submitting a PR** or **deploying to npm**, please use the [checklists in CONTRIBUTING.md](https://github.com/jsdom/abab/blob/master/CONTRIBUTING.md#checklists)
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### Remembering `atob` vs. `btoa`
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Here's a mnemonic that might be useful: if you have a plain string and want to base64 encode it, then decode it, `btoa` is what you run before (**b**efore - **b**toa), and `atob` is what you run after (**a**fter - **a**tob).
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