Update flip.md

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Angelos Chalaris
2020-01-13 10:07:21 +02:00
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--- ---
title: flip title: flip
tags: adapter,function,intermediate tags: function,intermediate
--- ---
Flip takes a function as an argument, then makes the first argument the last. Flip takes a function as an argument, then makes the first argument the last.
Return a closure that takes variadic inputs, and splices the last argument to make it the first argument before applying the rest. Return a closure that takes variadic inputs, and splices the last argument to make it the first argument before applying the rest.
```js ```js
const flip = fn => (first, ...rest) => fn(...rest, first); const flip = fn => (first, ...rest) => fn(...rest, first);
``` ```
```js ```js
let a = { name: 'John Smith' }; let a = { name: 'John Smith' };
let b = {}; let b = {};
const mergeFrom = flip(Object.assign); const mergeFrom = flip(Object.assign);
let mergePerson = mergeFrom.bind(null, a); let mergePerson = mergeFrom.bind(null, a);
mergePerson(b); // == b mergePerson(b); // == b
b = {}; b = {};
Object.assign(b, a); // == b Object.assign(b, a); // == b
``` ```