Oliver Jumpertz

Check If An Object Contains A Property

Category: JavaScript

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const symbol = Symbol("a");
const obj = {
propOne: 1,
[symbol]: 2,
"propOne" in obj; // true
symbol in obj; // true
0 in obj; // false


The in operator specifically checks whether an object has a specific key. So, instead of accessing the property and checking whether it is undefined, you can better mark your intent by just using in.

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