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MiSCapu
Asked: 2022-08-28 04:54:11 +0800 CST 2022-08-28 04:54:11 +0800 CST

When should Break be used on a Switch and when not?

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I have a doubt, I have created a basic function in JavaScript and I have no idea why this function works normally with break and without break .
When is it necessary to use that break in the switch conditional structure ?

This is the function:

function translator( num )
{
    switch ( num )
    {
        case 1:
            return 'one';
        case 2:
            return 'two';
        case 3:
            return 'three';
        case 4:
            return 'four';
        case 5:
            return 'five';
        default:
            return 'Enter a number!';
    }
}

let value = parseInt( prompt( 'Enter the number: ' ) );
let translateValue = translator( value );

document.write( translateValue );
javascript

1 Answers

  1. Best Answer

    If you look at the example that I put below, here if the break is necessary:

    function translator(num) {
  var result;
  switch (num) {
    case 1:
      result = 'one';
      break;
    case 2:
      result = 'two';
      break;
    case 3:
      result = 'three';
      break;
    case 4:
      result = 'four';
      break;
    case 5:
      result = 'five';
      break;
    default:
      result = 'Enter a number!';
  }
  
  return result;
}

let value = parseInt(prompt('Enter the number: '));
let translateValue = translator(value);

document.write(translateValue);

    The reason is as follows:

    • If you put a return in each case, the function executes it and no longer executes subsequent statements.
    • If what you do is assign a value to a variable, then you need the break so that it does not evaluate the other statements.

    In short, the break is used so that the script exits the execution (in this case) of the switch and does not evaluate the other conditions.

    In my example, if you remove the breaks, you will see that the switch will evaluate your number, but it will always end up returning the default, since that condition will also return true.

    I hope I have explained myself correctly.

    • 3