The Set object contains a list of unique values. We can store both primitive and object inside a Set.
let uniqueNum = new Set();
By using the add methods, we can add a new element to the set.
let uniqueNum = new Set();console.log("Adding Values")uniqueNum.add(1); // Set(1) {1}uniqueNum.add(2); // Set(2) {1, 2}console.log("Elements in set", uniqueNum); // Set(2) {1, 2}console.log("\nAdding duplicate value '1' to set")uniqueNum.add(1); // duplicate entry are not added.console.log("Elements in set after adding duplicate value", uniqueNum); // Set(2) {1, 2}
By using the has method, we can check if there is a value present in the set.
let uniqueNum = new Set();uniqueNum.add(1); // Set(1) {1}uniqueNum.add(2); // Set(2) {1, 2}console.log("Elements = ", uniqueNum); // Set(2) {1, 2}console.log("\nChecking if 1 is present in set",uniqueNum.has(1)); // trueconsole.log("Checking if 5 is present in set",uniqueNum.has(5)); // false
By using the size property, we can get the total number of items present in the set.
let uniqueNum = new Set();uniqueNum.add(1); // Set(1) {1}uniqueNum.add(2); // Set(2) {1, 2}console.log("\Set = ", uniqueNum); // 2console.log("Size of set", uniqueNum.size); // 2
By using the delete method, we can delete an item from the set. The delete method returns true if the item is present in the set, otherwise it returns false.
let uniqueNum = new Set();uniqueNum.add(1); // Set(1) {1}uniqueNum.add(2); // Set(2) {1, 2}console.log("deleting 1")uniqueNum.delete(1); // trueconsole.log("After deleting set =", uniqueNum);uniqueNum.delete(5); // false returned because 5 is not in set
By using the clear method, we can delete all the items in the set.
let uniqueNum = new Set();uniqueNum.add(1); // Set(1) {1}uniqueNum.add(2); // Set(2) {1, 2}console.log("\nClearing the set");uniqueNum.clear();console.log("After clearing values in set is", uniqueNum);
By using the forEach method, we can iterate through all the items of the set.
let fruits = new Set();fruits.add('🍏')fruits.add('🍎')fruits.add('🍊')fruits.forEach( fruit => console.log(fruit) );
let uniqueNum = new Set();console.log("Adding Values")uniqueNum.add(1); // Set(1) {1}uniqueNum.add(2); // Set(2) {1, 2}console.log("Elements in set", uniqueNum); // Set(2) {1, 2}console.log("\nAdding duplicate value '1' to set")uniqueNum.add(1); // duplicate entry are not added.console.log("Elements in set after adding duplicate value", uniqueNum); // Set(2) {1, 2}console.log("\nChecking if 1 is present in set",uniqueNum.has(1)); // trueconsole.log("Checking if 5 is present in set",uniqueNum.has(5)); // falseconsole.log("\nSize of set", uniqueNum.size); // 2console.log("\ndeleting 1")uniqueNum.delete(1); // trueconsole.log("After deleting set is", uniqueNum);uniqueNum.delete(5); // falseconsole.log("\nClearing the set");uniqueNum.clear();console.log("After clearing values in set is", uniqueNum);// using foreachconsole.log("\n\nUsing for each to prrint elements in set")let fruits = new Set();fruits.add('🍏')fruits.add('🍎')fruits.add('🍊')fruits.forEach( fruit => console.log(fruit) );
We can create a new set with an array or string.
//using arrayconsole.log("Creating set from Array");let fruits = new Set( ['🍏', '🍎', '🍊'] );console.log(fruits); // Set(3) {"🍏", "🍎", "🍊"}// using stringconsole.log("\nCreating set from String");fruits = new Set( '🍏🍎🍊🍇');console.log(fruits); // Set(4) {"🍏", "🍎", "🍊", "🍇"}
We can add an array or object to a set.
let setTest = new Set([1,2]);console.log(setTest); // Set(2) {1, 2}console.log("\n Adding Array");let arr = [1,2];setTest.add(arr);setTest.add([1,2]); //reference of arr is different from reference of [1,2]. So it is considered as new element.setTest.add(arr); // this will be skippedconsole.log(setTest); // Set(4) {1, 2, [1,2], [1,2]}console.log("\n Adding Object");setTest.add({ num : 10 });console.log(setTest);