[SOLVED] What is the value of an undefined parameter?


This Content is from Stack Overflow. Question asked by NeophyteLou

I’m having trouble understanding the behavior of the code below:

function multiplier(factor){
    return number => number * factor;

let twice = multiplier(2);

At the function call multiplier(2), the value of 2 is returned to the binding twice, which is 2, but how so? This implies that the return statement would evaluate to 1 * 2, but the parameter number was never assigned a value. I was expecting undefined * 2, instead which would return undefined. Why is the parameter number assigned a value of 1?


What let twice = multiplier(2); does is stored following function in twice variable

function(number) {
 // factor variable value was set here
 return number * 2;

When you called


It runs function stored in twice variable as following

function(5) {
  return 5 * 2;

Hence you got 10 on console.

This Question was asked in StackOverflow by NeophyteLou and Answered by Mursleen Amjad It is licensed under the terms of CC BY-SA 2.5. - CC BY-SA 3.0. - CC BY-SA 4.0.

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