Javascript bind() function-CodePudding

I need to write a function that accepts and function and an argument and returns the bound version of the the passed in function. Why doesn't my code work?

function bindToAnArg(func, arg){
 

     let myFunc = func.bind(arg);


return myFunc;

}

////Test

function add(num1, num2) {
  return num1   num2;
}

const addTwo = bindToAnArg(add, 2);

console.log(addTwo);

const twoPlusSix = addTwo(6);```

CodePudding user response：

The first argument of bind is what the value of this will be when the function is called. You probably should just pass null. This could would work:

function bindToAnArg(func, arg) {
    return func.bind(null, arg);
}

CodePudding user response：

The first argument to func.bind(...) must be the context (this) of the function. It's probably easier to avoid Function.prototype.bind altogether.

const bind = (f, ...a) => (...b) =>
  f(...a, ...b)

const add = (a, b) =>
  a   b

const addTwo =
  bind(add, 2)

console.log("2 plus 6 equals", addTwo(6))
// 2 plus 6 equals 8

const addMany = (...all) =>
  all.reduce(add, 0)

const addSome = bind(addMany, 1, 2, 3)

console.log("1 plus 2 plus 3 plus 4 plus 5 equals", addSome(4, 5))
// 1 plus 2 plus 3 plus 4 plus 5 equals 15