null coalescing operator javascript code example
Example 1: double question mark javascript
//Similar to || but only returns the right-hand operand if the left-hand is null or undefined
0 ?? "other" // 0
false ?? "other" // false
null ?? "other" // "other"
undefined ?? "other" // "other"
Example 2: nullish coalesing
Expression:
Left ?? Right
if left is null or undefined , then Right will be the value
const a = '' ;
const b = undefined;
const c = a ?? 'default' ; // will give c =''
const d = b ?? 'default' ; // wil give d = 'default'
Example 3: logical nullish operator javascript
function config(options) {
options.duration ??= 100;
options.speed ??= 25;
return options;
}
config({ duration: 125 }); // { duration: 125, speed: 25 }
config({}); // { duration: 100, speed: 25 }
Example 4: nullish-coalescing-operator
null || undefined ?? "foo"; // raises a SyntaxError
true || undefined ?? "foo"; // raises a SyntaxError