Create a variable within a JavaScript function that retains its value each time the function is called

Question

Create a variable within a JavaScript function that retains its value each time the function is called

Is there a way to declare a variable inside a JavaScript function so that it initializes once with the following behavior?

The initialization should occur only once.

function counter() {
  let_special count = 0;
  count++;
  if (count == 3) {
    count = 5;
  }
  return count;
}

let x = counter(); // x = 1
let y = counter(); // x = 2
let z = counter(); // x = 5
let m = counter(); // x = 6
let n = counter(); // x = 7

I vaguely remember there being a method to achieve this, but I cannot seem to find it on Google at the moment.

Thank you!

javascript typescript

Answer 1

Answer №1

How can a variable inside a JavaScript function retain its value across multiple calls?

One approach is to declare the variable outside of the function.

let count = 0;

function counter() {
  count++;
  if (count == 3) {
    count = 5;
  }
  return count;
}

let a = counter(); // a = 1
let b = counter(); // b = 2
let c = counter(); // c = 5
let d = counter(); // d = 6
let e = counter(); // e = 7

This can even be done within another function scope.

function makeCounter() {
  let count = 0;

  function counter() {
    count++;
    if (count == 3) {
      count = 5;
    }
    return count;
  }

  return counter;
}

let count = makeCounter();
let count2 = makeCounter();
let a = count(); // a = 1
let b = count(); // b = 2
let c = count(); // c = 5
let d = count(); // d = 6
let e = count(); // e = 7

let f = count2(); // f = 1
let g = count2(); // g = 2

Answer 2

How can a variable inside a JavaScript function retain its value across multiple calls?

One approach is to declare the variable outside of the function.

let count = 0;

function counter() {
  count++;
  if (count == 3) {
    count = 5;
  }
  return count;
}

let a = counter(); // a = 1
let b = counter(); // b = 2
let c = counter(); // c = 5
let d = counter(); // d = 6
let e = counter(); // e = 7

This can even be done within another function scope.

function makeCounter() {
  let count = 0;

  function counter() {
    count++;
    if (count == 3) {
      count = 5;
    }
    return count;
  }

  return counter;
}

let count = makeCounter();
let count2 = makeCounter();
let a = count(); // a = 1
let b = count(); // b = 2
let c = count(); // c = 5
let d = count(); // d = 6
let e = count(); // e = 7

let f = count2(); // f = 1
let g = count2(); // g = 2

Create a variable within a JavaScript function that retains its value each time the function is called

Answer №1

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