26 lines
645 B
Markdown
26 lines
645 B
Markdown
---
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title: flip
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tags: function,intermediate
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firstSeen: 2017-12-22T02:42:15+02:00
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lastUpdated: 2021-06-13T13:50:25+03:00
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---
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Takes a function as an argument, then makes the first argument the last.
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- Use argument destructuring and a closure with variadic arguments.
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- Splice the first argument, using the spread operator (`...`), to make it the last before applying the rest.
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```js
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const flip = fn => (first, ...rest) => fn(...rest, first);
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```
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```js
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let a = { name: 'John Smith' };
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let b = {};
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const mergeFrom = flip(Object.assign);
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let mergePerson = mergeFrom.bind(null, a);
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mergePerson(b); // == b
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b = {};
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Object.assign(b, a); // == b
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```
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