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

title, tags

title	tags
bind	function,object,intermediate

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

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

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!'