Why does the following code:
'%' in new Set('%');
return false?
And is the in operator faster on a set than on an array?
1 Answers
The in operator returns true if the specified property is in the specified object or its prototype chain.
It does not check if something belongs to a set. You should use Set.prototype.has for that.
const obj = { someKey: 'someValue' };
'someKey' in obj; // true
'someOtherKey' in obj; // false
const set = new Set([1,2,3]);
set.has(1); // true
set.has(4); // false
Regarding performance, please refer to this question
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