JavaScript - Set

Set

Set - MDN

The Set object lets you store unique values of any type, whether primitive values or object references.

let set = new Set(); set.add(1); set.add({ name: "kitty" }); console.log(set); // { 1, { name: 'kitty' } } 

Set objects are collections of values. You can iterate through the elements of a set in insertion order. A value in the Set may only occur once; it is unique in the Set's collection.

// A value in the Set may only occur once let set = new Set(); set.add(1); set.add({ name: "kitty" }); set.add(1); console.log(set); // { 1, { name: 'kitty' } } 

Value equality: 1.+0 & -0 are the same(ES6); 2.NaN & undefined can also be stored in a Set. All NaN values are equated(NaN is considered the same as NaN, even though NaN !== NaN)

//1.`+0` & `-0` are the same(ES6) let set1 = new Set(); set1.add(+0); set1.add(-0); console.log(set1); // { 0 } //2.`NaN` & `undefined` can also be stored in a Set. All `NaN` values are equated(NaN is considered the same as NaN, even though NaN !== NaN) let set2 = new Set(); set2.add(NaN); set2.add(undefined); set2.add(NaN); console.log(set2); // { NaN, undefined } 

Constructor - Set()
The Set constructor lets you create Set objects that store unique values of any type, whether primitive values or object references.
Syntax - new Set(iterable)

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

Instance properties & methods

• size - Returns the number of values in the Set object.

 let set = new Set([1, 2, 3, 4, 5]); console.log(set.size); // 5 

• clear() - Removes all elements from the Set object.

 let set = new Set([1, 2, 3, 4, 5]); set.clear(); console.log(set); // {} 

• delete() - The delete() method removes a specified value from a Set object, if it is in the set.

 let set = new Set([1, 2, 3, 4, 5]); set.delete(1); console.log(set); // { 2,3,4,5 } 

• forEach() - The forEach() method executes a provided function once for each value in the Set object, in insertion order.

 let set = new Set([1, 2, 3, 4, 5]); set.forEach((element) => console.log(element)); // 1 -> 2 -> 3 -> 4 -> 5