javascript - How to compare 2 boolean values in TypeScript - Stack Overflow

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I'm trying to pare to boolean value in a if. I would like to do something like this:

value1 = false;
value2 = true;

if (value1 === value2) {
  ... Some code ...
}

In Java you can use Booleanpare(boolean a, boolean b), but I can't find something equal in TypeScript.
For context, Booleanpare(boolean a, boolean b) returns:

• 0 if a is equal to b,
• a negative value if a is false and b is true,
• a positive value if a is true and b is false.

Thanks for you help

Edited: to show the message I get

This condition will always return 'false' since the types 'true' and 'false' have no overlap

I'm trying to pare to boolean value in a if. I would like to do something like this:

value1 = false;
value2 = true;

if (value1 === value2) {
  ... Some code ...
}

In Java you can use Boolean.pare(boolean a, boolean b), but I can't find something equal in TypeScript.
For context, Boolean.pare(boolean a, boolean b) returns:

• 0 if a is equal to b,
• a negative value if a is false and b is true,
• a positive value if a is true and b is false.

Thanks for you help

Edited: to show the message I get

This condition will always return 'false' since the types 'true' and 'false' have no overlap

• javascript
• typescript

Share Improve this question Follow edited May 7, 2024 at 11:38 aioobe 421k114114 gold badges828828 silver badges839839 bronze badges asked Dec 19, 2020 at 14:40 JBDJBD 74111 gold badge1515 silver badges3030 bronze badges 9

• What's wrong with what you wrote? – tehhowch Commented Dec 19, 2020 at 14:42
• 1 === is how to pare two boolean values. – jonrsharpe Commented Dec 19, 2020 at 14:42
• 1 === checks for equality. Boolean.pare checks for ordering (returns less than zero if a is false and b is true, zero if they are equal or more than zero if a is true and b is false - is that the behavior you're looking for? – Mureinik Commented Dec 19, 2020 at 14:42
• 3 I've taken the liberty of adding a description for Boolean.pare to your question since it seems you're being downvoted due to being misunderstood. – Etheryte Commented Dec 19, 2020 at 14:47
• 1 dw someone and I upvoted you so at least you won't lose reputation – Pauline Nemchak Commented Dec 19, 2020 at 14:57

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3 Answers 3

Sorted by: Reset to default 5

Javascript doesn't have a builtin that's parable to Java's Boolean.pare(). In fact, the Boolean class has nearly nothing in it, outside the constructor, toString() and valueOf().

If you want to replicate the functionality yourself, you can use the Number constructor.

function booleanCompare(a: boolean, b: boolean) {
    return Number(a) - Number(b);
}

This can be used to reach all possible outmings:

const Result = {
  first: 0, // A: 0, B 0
  second: 1, // A: 1, B 0
  third: -1, // A: 0, B 1
  forth: 2, // A: 1, B 1
  get: (A: boolean, B: boolean) => (Number(A) - Number(B))
}

const f = () => {
  const A = true;
  const B = true;

  switch(Result.get(A, B)) {
    case Result.first:
      // To something
      break;
    case Result.second:
      // To something
      break;
    case Result.third:
      // To something
      break;
    case Result.forth:
      // To something
  }
}

In TypeScript, you can directly pare boolean values using the strict equality operator (===). If you want to replicate the behavior of Boolean.pare(boolean a, boolean b) in TypeScript, you can write a simple function to achieve that:

function pareBooleans(a: boolean, b: boolean): number {
    if (a === b) {
        return 0;
    } else if (a === false && b === true) {
        return -1;
    } else {
        return 1;
    }
}
const value1: boolean = false;
const value2: boolean = true;

const parisonResult: number = pareBooleans(value1, value2);

This function replicates the behavior of Boolean.pare(boolean a, boolean b) where:

• It returns 0 if a is equal to b.
• It returns a negative value if a is false and b is true.
• It returns a positive value if a is true and b is false.

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