in

`prop in obj`

⟩ ⟩ ⟩ ⟩ ⟩ in

// ⭐️ check if `prop` is property of `obj` (including inherited)
prop in obj        // ⭐️ prop: string-convertable expression

table of operators

for-in vs. for-of vs. in

replit：

let point = {x: 1, y: 2};
let array = [1, 2, 3];

'x' in point,            // true
'z' in point,            // false
'toString' in point,     // true    (inherited)

'0' in array,            // true
1 in array,              // true    (1 -> '1')
3 in array,              // false   (3 -> '3', no such prop)
'toString' in array,     // true    (inherited)

Previouscomparison operator Nextinstanceof

Last updated 2 years ago

Was this helpful?