error Unnecessary use of boolean literals in conditional expression no-unneeded-ternary

Question

I am trying this code in atom with ESLint

Code snippet:

$scope.IsVisible = false;
$scope.ShowHide = function () {
  $scope.IsVisible = $scope.IsVisible ? false : true; // error
};

Got this ESLint error: error Unnecessary use of boolean literals in conditional expression no-unneeded-ternary

Tried with these solutions solution 1 and solution 2, but error is not fixed. Furthermore, code works fine in editor without ESLint.

`$scope.IsVisible = !$scope.IsVisible;` – Andreas Mar 09 '17 at 21:41 — Andreas, Mar 09 '17 at 21:41

score 18 · Accepted Answer · answered Mar 09 '17 at 21:40

18

Try the good way =). No need to use statements in this case.

$scope.IsVisible = !$scope.IsVisible;

answered Mar 09 '17 at 21:40

lin

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7

If, like me, you need to check for a `true` value, use the double bang: `!!$scope.IsVisible` – kylesimmonds Apr 27 '17 at 04:50

score 3 · Answer 2 · answered Apr 24 '21 at 08:53

In my case, I wanted to assign a value to my boolean, according to a variable that was either an object or null.

As kylesimmonds stated, the double bang !! operator can be used.

const myObject: SomeObjectType | null;
...

const isObjectExistent: boolean = !!myObject;
/*
  instead of:
  const isObjectExistent: boolean = myObject? true : false;
*/

Check: What is the !! (not not) operator in JavaScript?

error Unnecessary use of boolean literals in conditional expression no-unneeded-ternary

2 Answers2