30-seconds-of-code/snippets/flip.md

title, tags, expertise, cover, firstSeen, lastUpdated

title	tags	expertise	cover	firstSeen	lastUpdated
Flip function arguments	function	intermediate	blog_images/interior-11.jpg	2017-12-22T02:42:15+02:00	2021-06-13T13:50:25+03:00

Takes a function as an argument, then makes the first argument the last.

• Use argument destructuring and a closure with variadic arguments.
• Splice the first argument, using the spread operator (...), to make it the last before applying the rest.

const flip = fn => (first, ...rest) => fn(...rest, first);

let a = { name: 'John Smith' };
let b = {};
const mergeFrom = flip(Object.assign);
let mergePerson = mergeFrom.bind(null, a);
mergePerson(b); // == b
b = {};
Object.assign(b, a); // == b