Arrays and Objects

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Section 4 of 4

Object Methods & Iteration

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Object Methods & Iteration

Topic Overview

Take your time to understand each concept. Practice with the examples below!

Objects can do more than just store data - they can also contain functions (called methods) and we can loop through their properties!

Object Methods (functions inside objects):

const calculator = {
  name: "Super Calc",
  add: function(a, b) {
    return a + b;
  },
  multiply: function(a, b) {
    return a * b;
  }
};
// Using methods:
calculator.add(5, 3);      // 8
calculator.multiply(4, 7); // 28

Modern method syntax (ES6):

const dog = {
  name: "Buddy",
  age: 3,
  bark() {  // Shorter syntax!
    return "Woof! My name is " + this.name;
  }
};

Iterating through objects:

•Object.keys() - Get all property names

const keys = Object.keys(person);  // ["name", "age", "city"]

•Object.values() - Get all values

const values = Object.values(person);  // ["Alice", 25, "Boston"]

•Object.entries() - Get key-value pairs

const entries = Object.entries(person);  // [["name", "Alice"], ["age", 25], ["city", "Boston"]]

•for...in loop - Loop through properties

for (let key in person) {
  console.log(key + ": " + person[key]);
}

Real example - user profile:

const user = {
  username: "coder123",
  score: 150,
  level: 5,
  levelUp() {
    this.level++;
    this.score += 50;
  }
};

Ready to practice? Try the exercise below to reinforce your learning!

Try it yourself

Create an object with methods and iterate through its properties using Object.keys().

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