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

flip

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.

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