Nullish coalescing in JavaScript
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The nullish coalescing operator (??) in JavaScript returns the right-hand operand when the left-hand is null or undefined. It cannot be directly combined with logical operators like '&&' and '||', as attempting to do so results in a syntax error unless parenthesis are used. The document also discusses how '||' differs from '??' in handling various values.
Nullish coalescing in JavaScript
- 2. Nullish Coalescing “??” The nullish coalescing operator (??) is a logical operator that returns its right-hand side operand when its left-hand side operand is null or undefined. Syntax, leftExpr ?? rightExpr Note: It is not possible to combine both the AND ‘&&’ and OR operators ‘||’ directly with ‘??’. null || undefined ?? ; // raises a SyntaxError However, to solve it we need to provide parenthesis explicitly, (null || undefined) ?? ; // returns
- 3. Problem with || 0 || // ‘’ || // false || // undefined || // null || // NAN || // Solution with ?? 0 ?? // 0 ‘’ ?? // ‘’ false ?? // false undefined ?? // null ?? // NAN ?? // NAN How “||” different from “??”