JS: Set.prototype.has

By Xah Lee. Date: 2017-02-17. Last updated: 2017-09-05.

New in ES2015.

set_obj.has(value)

Return true if value is in set. Else, false.

const s = new Set([3,4,5]);

// check existence

console.log ( s.has (5) ); // true
console.log ( s.has (99) ); // false

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