JavaScript Object & Array Scenario based Questions

1. User Profile Update

Update an object property and add a new one.

const user = {
  name: "Vijay",
  age: 25,
  email: "[e-mail]"
};

user.email = "[e-mail]";
user.isActive = true;

console.log(user);

Output:

{
  name: "Vijay",
  age: 25,
  email: "[e-mail]",
  isActive: true
}

2. Shopping Cart Total

Calculate total price from an array of objects.

const cart = [
  { name: "Shirt", price: 500 },
  { name: "Shoes", price: 1500 },
  { name: "Cap", price: 300 }
];

const total = cart
  .map(val => val.price)
  .reduce((acc, val) => acc + val, 0);

console.log(total);

Output:

2300

3. Find Specific Object

Find a user with a specific name.

const users = [
  { name: "Vijay", age: 25 },
  { name: "Arun", age: 30 },
  { name: "Kumar", age: 28 }
];

const output = users.filter(n => n.name === "Arun");

console.log(output);

Output:

[{ name: "Arun", age: 30 }]

4. Add Item to Array & Filter

Add a new product and filter data.

const products = [
  { name: "Shirt", price: 500 },
  { name: "Shoes", price: 1500 }
];

products.push({ name: "Pant", price: 1750 });

console.log(products);

const newProdut = products.filter(
  n => n.name !== "Shoes" && n.price > 1000
);

console.log(newProdut);

Output:

[
  { name: "Shirt", price: 500 },
  { name: "Shoes", price: 1500 },
  { name: "Pant", price: 1750 }
]

[
  { name: "Pant", price: 1750 }
]

5. Count Items in Object

Find total values inside an object.

const fruits = {
  apple: 2,
  banana: 5,
  mango: 3
};

const output = Object.values(fruits).reduce((acc, n) => acc + n);

console.log(output);

Output:

10

6. Convert Array to Object

Convert array into object with values as keys.

const users = ["Vijay", "Arun", "Kumar"];

const dub = Object.fromEntries(
  users.map(v => [v, true])
);

console.log(dub);

Output:

{
  Vijay: true,
  Arun: true,
  Kumar: true
}

Comments

[Jon Randy 🎖️]

Much simpler:

// Cart total
const cart = [
  { name: "Shirt", price: 500 },
  { name: "Shoes", price: 1500 },
  { name: "Cap", price: 300 }
]

const total = cart.reduce( (total, { price }) => total + price, 0 )
console.log(total)

Your version returns an array containing the user. This version returns the found user (which is probably preferable), and stops looking when the user is found - more efficient:

// Find User
const users = [
  { name: "Vijay", age: 25 },
  { name: "Arun", age: 30 },
  { name: "Kumar", age: 28 }
]

const output = users.find(n => n.name === "Arun")
console.log(output)