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javascriptfunctionreturn

Can you use parent function variables inside a returned function in javascript?

Here's the function code:

function TestFunction(number){
  return function(e){
    return `${number}`;
  }
}

When I use it on google's devtools command line it returns:

function(e){
  return `${number}`;
}

So it looks like the function returned is not created with the number I give to TestFunction, instead it takes the string just like it was written. I have tried to use concatenation instead of interpolation but still not working. What can I do?

Solution

  • There is indeed a closure around the second function, so it will have memory of what num is.

    function a(num) {
  return function b() {
    return `${num}`;
  }
}

const c = a(6);

console.log(c());