How can I implement logics without if else, switch or a built-in function in javascript

Question

Suppose we have function, which returns 3 when passing 5 to it and return 5 when passing 3 to it. I know it is very easy with if else and switch.

for example

function countReturn(number){
  if(number === 3){
  return 5
 }

  if(number === 5){
  return 3
 }

}

But how can I implement the same logic without if else, switch or any built-in function?

You can use the Ternary operator. `return number === 3 ? 5 : 3` — Nawaf Khalifah, Nov 05 '21 at 11:50
What is actually the goal here? What should `countReturn(1)` or `countReturn(12)` produce? — VLAZ, Nov 05 '21 at 11:52
@PatrickEvans, looks like [this](https://stackoverflow.com/questions/6911235/is-there-a-better-way-of-writing-v-v-0-1-0/31028514#31028514). — Nina Scholz, Nov 05 '21 at 11:57

score 2 · Accepted Answer · answered Nov 05 '21 at 11:47

2

You can store the return values in an array:

function countReturn(n) {
  let a = [,,,5,,3];
  return a[n];
}

That will return undefined for other inputs, just like your original code.

answered Nov 05 '21 at 11:47

Pointy

Marking your answer. Although its not valid to provide the empty elements but it does work the logic. – Wahas Ali Mughal Nov 05 '21 at 12:27
@WahasAliMughal it is valid to have empty elements in an array literal. – Pointy Nov 05 '21 at 12:51

score 1 · Answer 2 · answered Nov 05 '21 at 11:47

1

You could take the sum (3 + 5) and return the delta of the actual number.

function threeOrFive(value) {
    return 8 - value;
}

console.log(threeOrFive(3)); // 5
console.log(threeOrFive(5)); // 3

answered Nov 05 '21 at 11:47

Nina Scholz

`threeOrFive(1)` seems to return `7`, rather than OP's function which would return `undefined` in that case. Not sure what OP actually wants to happen with non-3 and non-5 values, though. – VLAZ Nov 05 '21 at 11:50

Thibaud · Answer 3 · 2021-11-05T11:59:08.350

1

you can so it with ternary like this

return number === 3 ? 5 : (number === 5 ? 3 : 0);

Or you can do it with object

const obj = {
  "5": 3,
  "3": 5
};
return obj[number];

edited Nov 05 '21 at 11:59

answered Nov 05 '21 at 11:48

Thibaud

I'm not sure a conditional expression counts as something different to an `if`. – VLAZ Nov 05 '21 at 11:49
@VLAZ I add a methode with object. In case ternary aren't allowed – Thibaud Nov 05 '21 at 12:00
Ternary is a conditional statement. So can't mark your answer. – Wahas Ali Mughal Nov 05 '21 at 12:12
@WahasAliMughal I understand, just consider the object methode for your futur developement – Thibaud Nov 05 '21 at 12:13

score 0 · Answer 4 · answered Nov 05 '21 at 11:48

0

We can return the xored value between 5 and 3:

return number ^ 6

Implementing the same logic, it would return 3 when given 5 and vice versa

answered Nov 05 '21 at 11:48

CodeCop

4 Answers4