Set in js code example

Example 1: array to set javascript

const myArray = [1,2,3,1,5,8,1,2,9,4];
const unique = [...new Set(myArray)]; // [1, 2, 3, 5, 8, 9, 4]

const myString = ["a","b","c","a","d","b"];
const uniqueString = [...new Set(myString)]; //["a", "b", "c", "d"]

Example 2: set js

// Use to remove duplicate elements from the array 

const numbers = [2,3,4,4,2,3,3,4,4,5,5,6,6,7,5,32,3,4,5]

//spreading numbers of the object into an array using the new operator
console.log([...new Set(numbers)]) 

// [2, 3, 4, 5, 6, 7, 32]

Example 3: set in javascript

let mySet = new Set()

mySet.add(1)           // Set [ 1 ]
mySet.add(5)           // Set [ 1, 5 ]
mySet.add(5)           // Set [ 1, 5 ]
mySet.add('some text') // Set [ 1, 5, 'some text' ]
let o = {a: 1, b: 2}
mySet.add(o)

mySet.add({a: 1, b: 2})   // o is referencing a different object, so this is okay

mySet.has(1)              // true
mySet.has(3)              // false, since 3 has not been added to the set
mySet.has(5)              // true
mySet.has(Math.sqrt(25))  // true
mySet.has('Some Text'.toLowerCase()) // true
mySet.has(o)       // true

mySet.size         // 5

mySet.delete(5)    // removes 5 from the set
mySet.has(5)       // false, 5 has been removed

mySet.size         // 4, since we just removed one value

console.log(mySet)
// logs Set(4) [ 1, "some text", {…}, {…} ] in Firefox
// logs Set(4) { 1, "some text", {…}, {…} } in Chrome

Example 4: set in javascript

// set is used for storing unique values
const firstSet = new Set([1, 2, 3]);

firstSet.add('hi'); //adding value to set

firstSet.add(3); //this will not give any error and it will also not be added

firstSet.delete('hi');//removing value from set

console.log(firstSet.has('hi'));//checking 'hi' is in the set or not

// showing all values in the set
console.log(firstSet);
for (const entry of firstSet.values()) {
    console.log(entry);

Example 5: set js

let text = 'India'

let mySet = new Set(text)  // Set ['I', 'n', 'd', 'i', 'a']
mySet.size  // 5

//case sensitive & duplicate ommision
new Set("Firefox")  // Set(7) [ "F", "i", "r", "e", "f", "o", "x" ]
new Set("firefox")  // Set(6) [ "f", "i", "r", "e", "o", "x" ]

Example 6: set js

// iterate over items in set
// logs the items in the order: 1, "some text", {"a": 1, "b": 2}, {"a": 1, "b": 2}
for (let item of mySet) console.log(item)

// logs the items in the order: 1, "some text", {"a": 1, "b": 2}, {"a": 1, "b": 2}
for (let item of mySet.keys()) console.log(item)

// logs the items in the order: 1, "some text", {"a": 1, "b": 2}, {"a": 1, "b": 2}
for (let item of mySet.values()) console.log(item)

// logs the items in the order: 1, "some text", {"a": 1, "b": 2}, {"a": 1, "b": 2}
// (key and value are the same here)
for (let [key, value] of mySet.entries()) console.log(key)

// convert Set object to an Array object, with Array.from
let myArr = Array.from(mySet) // [1, "some text", {"a": 1, "b": 2}, {"a": 1, "b": 2}]

// the following will also work if run in an HTML document
mySet.add(document.body)
mySet.has(document.querySelector('body')) // true

// converting between Set and Array
mySet2 = new Set([1, 2, 3, 4])
mySet2.size                    // 4
[...mySet2]                    // [1, 2, 3, 4]

// intersect can be simulated via
let intersection = new Set([...set1].filter(x => set2.has(x)))

// difference can be simulated via
let difference = new Set([...set1].filter(x => !set2.has(x)))

// Iterate set entries with forEach()
mySet.forEach(function(value) {
  console.log(value)
})

// 1
// 2
// 3
// 4