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JavaScript Sets

المعرفة:: JavaScript
الحالة:: ملاحظة_مؤرشفة
المراجع:: The Complete JavaScript Course 2022 From Zero to Expert

Sets are collections of unique values. Items order is irrelevant and there’s no access by index.

// Sets  
const ordersSet = new Set(["Pasta", "Pizza", "Pizza", "Risotto", "Pasta", "Pizza"]);  
console.log(ordersSet); // {"Pasta", "Pizza", "Risotto"}  

console.log(new Set("Jonas")); // {"J", "o", "n", "a", "s"}

Methods¶

Size¶

console.log(ordersSet.size); // 3

Has¶

Check if an element is in a set. Similar to include method in arrays.

console.log(ordersSet.has("Pizza")); // true  
console.log(ordersSet.has("Bread")); // false

Add¶

ordersSet.add("Garlic Bread");  
ordersSet.add("Garlic Bread");  
console.log(ordersSet); // {"Pasta", "Pizza", "Risotto", "Garlic Bread"}

Delete¶

ordersSet.delete("Risotto");  
console.log(ordersSet); // {"Pasta", "Pizza", "Garlic Bread"}

Clear¶

// ordersSet.clear();  
console.log(ordersSet); // {}

Iteration¶

for (const order of ordersSet) console.log(order);

Examples¶

Remove duplicates form an array¶

const staff = ["Waiter", "Chef", "Waiter", "Manager", "Chef", "Waiter"];  
// const staffUnique = new Set(staff);  
console.log(staffUnique); // {'Waiter', 'Chef', 'Manager'}  
const staffUnique = [...new Set(staff)];  
console.log(staffUnique); // ['Waiter', 'Chef', 'Manager']

Get size of unique element of an array or string¶

console.log(new Set(["Waiter", "Chef", "Waiter", "Manager", "Chef", "Waiter"]).size); // 3  
console.log(new Set("jonasschmedtmann").size); // 1

Last update : August 14, 2023
Created : August 23, 2022

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