30秒学会 JavaScript 片段 – Bind function context

Creates a function that invokes fn with a given context, optionally prepending any additional supplied parameters to the arguments.

• Return a function that uses Function.prototype.apply() to apply the given context to fn.
• Use the spread operator (...) to prepend any additional supplied parameters to the arguments.

代码实现

const bind = (fn, context, ...boundArgs) => (...args) =>
  fn.apply(context, [...boundArgs, ...args]);

function greet(greeting, punctuation) {
  return greeting + ' ' + this.user + punctuation;
}
const freddy = { user: 'fred' };
const freddyBound = bind(greet, freddy);
console.log(freddyBound('hi', '!')); // 'hi fred!'

翻译自：https://www.30secondsofcode.org/js/s/bind-function-context