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A Practical Example of Nullish Coalescing
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4 min readJun 3, 2020
Nullish coalescing is a brand new logical operator (??) for the JavaScript programming language. It was released along with a whole slew of other new features on April 2nd this year as part of ECMAScript version 2020 (or ES2020).
This new operator is very similar to the logical OR (||) operator, with the exception that it only returns the right-hand side operand when the left-hand side operand evaluates to being nullish. This means that nullish coalescing returns the right-hand side operand when the left-hand side evaluates to undefined or null, but not false, 0, or "" as it will with the logical OR operator.
// These will return the left-hand side operand
// with nullish coalescing, but not ORfalse || true // returns true
false ?? true // returns false0 || true // returns true
0 ?? true // returns 0"" || true // returns true
"" ?? true // returns ""// These will return the right-hand side operand
// with nullish coalescing, same as ORundefined || true // returns true
undefined ?? true // returns truenull || true // returns true
null ?? true // returns true
