CODEWITHSUNDEEP
javascript
user3253748
user3253748

Reputation: 89

JavaScript if statement evaluates only first condition

My if statement evaluates only 1st condition, second one after || is overlooked. How to fix this?

function validateAge(input) {
  if ((input.value < 0 || input.value > 110) || (input.value.match(/[^0-9]/))) {
    input.setCustomValidity("Dozwolony zakres: od 0 do 110");
  } else {
    input.setCustomValidity("");
  }
}

Upvotes: 2

Views: 2538

Answers (1)

Minko Gechev
Minko Gechev

Reputation: 25682

Well, there is something called lazy evaluation. The JavaScript interpreter won't evaluate something if it is unnecessary to do so. In the disjunction (||) when the first statement evaluates to true then the whole expression is true, so that's why when the JavaScript interpreter evaluates: (input.value < 0 || input.value > 110) to true, it is not necessary to calculate the value of (input.value < 0 || input.value > 110).

If (input.value.match(/[^0-9]/)) is "show stopper" you can proceed the following way:

if ((input.value.match(/[^0-9]/)) || (input.value < 0 || input.value > 110))

If I understood correctly you need something like:

function validateValue(input) {
  var value = input.value;
  if (/^\d+$/.test(value)) {
    value = parseInt(value, 10);
  } else {
    return false;
  }
  return value < 0 || value > 110;
}

Upvotes: 7

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