I have a ternary operator dir === 'next' ? ++$currentSlide : --$currentSlide; in my JS used to increment of decrement an integer. when I run my script in grunt JSHint hightlights this line as Expected an assignment or function call and instead saw an expression.

Can anyone advise where I'm going wrong with this? Should I set my condition up differently etc?

I have a ternary operator dir === 'next' ? ++$currentSlide : --$currentSlide; in my JS used to increment of decrement an integer. when I run my script in grunt JSHint hightlights this line as Expected an assignment or function call and instead saw an expression.

Can anyone advise where I'm going wrong with this? Should I set my condition up differently etc?

• javascript

5 Answers 5

You are misusing the conditional operator as an if statement, that's why you are getting that note. The real work in the code is done as a side effect of the expression, and the result of the expression is ignored.

As a real if statement, it would be:

if (dir === 'next') {
  ++$currentSlide;
} else {
  --$currentSlide;
}

You can use the conditional operator if you use it as an actual expression:

$currentSlide += dir === 'next' ? 1 : -1;

In general, for disabling the 'Expected an assignment or function call and instead saw an expression.' warning, you can do /* jshint expr: true */

Does it pass if you write it like this?

$currentSlide = (dir === 'next' ? $currentSlide + 1 : $currentSlide - 1);

Linters and hinters usually don't like in/decrements because they're sensitive to bugs.

Try this syntax:

$currentSlide = (dir === 'next' ? $currentSlide+1 : $currentSlide-1);

make ternary operator in to if else condition

Before:

(pbook.id === book.id ? book.shelf = pbook.shelf : "none");

After:

                     if(pbook.id === book.id){
                        return book.shelf = pbook.shelf
                      } else {
                        return "none"
                      };