30秒学会 JavaScript 片段 – call.md

title: call
tags: function,intermediate

Given a key and a set of arguments, call them when given a context. Primarily useful in composition.

Use a closure to call a stored key with stored arguments.

代码片段

const call = (key, ...args) => context => context[key](...args);

使用样例

Promise.resolve([1, 2, 3])
  .then(call('map', x => 2 * x))
  .then(console.log); // [ 2, 4, 6 ]
const map = call.bind(null, 'map');
Promise.resolve([1, 2, 3])
  .then(map(x => 2 * x))
  .then(console.log); // [ 2, 4, 6 ]