Shorthand way to write Conditional in Javascript-CodePudding

I usually run into writing conditionals like this and I'm wondering if there a short hand way to write something similar below without calling a function

const currentValue = this.props.book.location.areaValueInDollars ? this.props.book.location.areaValueInDollars : 0;

CodePudding user response：

Use nullish coalescing operator:

this.props.book.location.areaValueInDollars || 0

More on the subject here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing_operator

CodePudding user response：

You can use short-circuiting and the Logical OR operator.

const currentValue = window['a'] || 0; 

console.log(currentValue);

If the variable exists, then the first operand will return true, causing it to "short circuit" and be returned. The second operand is only evaluated if the first is false, since the expression is evaluated from left to right.

Using the Logical OR operator has a caveat though. If the variable is 0, null, undefined... (for full list, see Falsy values), it will return false.

To solve this, we can use the Nullish coalescing operator, which will only return the right-hand side operand if the left operand is null or undefined. Like so:

const currentValue = window['a'] ?? 0; 

console.log(currentValue);