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ES6 sets a collection that cannot contain duplicates

create a set in ES6 by passing an array into the constructor

let set = new Set([1, 2, 3, 3, 4, 5, 5, 5, 6]);

console.log(set.size); // 6
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the array I passed in contains duplicates. But the set essentially strips them out leaving a collection of 6 unique items
You also have access to the add() method

let set = new Set();


console.log(set.size); // 2
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Finally, there's the has() method, which is very useful. This method allows you to check if an item exists

console.log(set.has(1)); // true
console.log(set.has('two')); // true
console.log(set.has(3)); // false
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Try it on jsbin

Top comments (1)

dmerand profile image
Donald Merand

It's amazing how many problems you can solve by having the proper data structure! It's nice to see JavaScript implementing these things as native language constructs.