Function.prototype.cbind = function (...outer_args) {

    let that = this,

        params = outer_args.slice(1),

        obj = outer_args[0];

​

    return function (...inner_args) {

        that.apply(obj, [...params, ...inner_args]);

    }

}

Function.prototype.myBind = function (...args) {

  const that = this

  const params = args.slice(1)

  return function (...args2) {

    that.apply(args[0], [...params, ...args2])

  }

}