23 lines
540 B
Markdown
23 lines
540 B
Markdown
---
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title: call
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tags: function,intermediate
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---
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Given a key and a set of arguments, call them when given a context. Primarily useful in composition.
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Use a closure to call a stored key with stored arguments.
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```js
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const call = (key, ...args) => context => context[key](...args);
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```
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```js
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Promise.resolve([1, 2, 3])
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.then(call('map', x => 2 * x))
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.then(console.log); // [ 2, 4, 6 ]
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const map = call.bind(null, 'map');
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Promise.resolve([1, 2, 3])
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.then(map(x => 2 * x))
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.then(console.log); // [ 2, 4, 6 ]
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```
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