bind es6

es6-bind.js

function foo(a, b) {
console.log("___A___", a);
console.log("___B___", b);
  return a + b + this.c;
}

function bind(fn, ctx, ...args) {
  if(typeof(fn) !== 'function') {
  	throw new TypeError("error");
  }
  
  return function(args2) {
  	return fn.apply(ctx, [...args, ...args2]) // order important
  }
}

const f1 = bind(foo, { c: 42 });
const f2 = bind(foo, { c: 42 }, 10);

console.assert(f1(1, 2) === 45, "f1(1, 2) === 45");
console.assert(f2(1, 2) === 53, "f2(1, 2) === 53");