JS Tip of the Day: Nullish Coalescing Operator

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Nullish Coalescing Operator
Version: ES2020
Level: Intermediate

The nullish coalescing operator (??) is also new to ES2020. It works much like logical OR (||) except that it will short circuit (or return) for non-null, non-undefined falsy values such as false, 0, and empty strings whereas OR would not. This is useful for setting defaults that may include these kinds of values.

let initialValue = 0;
let x = initialValue || 1;
let y = initialValue ?? 1;
console.log(x); // 1
console.log(y); // 0

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