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How to access an object through another object in JavaScript?

Javascript Web Development Object Oriented Programming

In JavaScript, you can access properties and methods of one object from another object by referencing them directly. This technique is useful for sharing data between objects or creating relationships.

Basic Property Access

The simplest way is to reference properties directly from another object:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Object Access Example</title>
</head>
<body>


<button id="showBtn">CLICK HERE</button>

<script>
// First object with properties and method
let obj = {
    firstName: "Rohan",
    lastName: "Sharma",
    welcome() {
        return "Welcome " + this.firstName + " " + this.lastName;
    }
};

// Second object accessing first object's properties
let obj2 = {
    firstName: "Mohit",
    lastName: obj.lastName,           // Direct property access
    welcomeString: obj.welcome(),     // Method call result
    originalObj: obj                  // Store reference to entire object
};

document.getElementById("showBtn").addEventListener("click", () => {
    let output = `
        obj2.firstName = ${obj2.firstName}<br>
        obj2.lastName = ${obj2.lastName}<br>
        obj2.welcomeString = ${obj2.welcomeString}<br>
        Original object name: ${obj2.originalObj.firstName}
    `;
    document.getElementById("result").innerHTML = output;
});
</script>
</body>
</html>

Dynamic Property Access

You can also access object properties dynamically using bracket notation:

let person = {
    name: "Alice",
    age: 25,
    city: "New York"
};

let employee = {
    id: 101,
    department: "IT",
    // Access person's properties dynamically
    getPersonInfo: function(property) {
        return person[property];
    }
};

console.log(employee.getPersonInfo("name"));  // Alice
console.log(employee.getPersonInfo("age"));   // 25
console.log(employee.getPersonInfo("city"));  // New York

Alice
25
New York

Method Borrowing with call()

You can borrow methods from one object and use them with another object's context:

let person1 = {
    firstName: "John",
    lastName: "Doe",
    getFullName: function() {
        return this.firstName + " " + this.lastName;
    }
};

let person2 = {
    firstName: "Jane",
    lastName: "Smith"
};

// Borrow person1's method for person2
let person2Name = person1.getFullName.call(person2);
console.log(person2Name);  // Jane Smith

// Store the borrowed method
person2.getFullName = person1.getFullName;
console.log(person2.getFullName());  // Jane Smith

Jane Smith
Jane Smith

Comparison of Access Methods

Method	Use Case	Dynamic?
Direct property access (`obj.property`)	Known property names	No
Bracket notation (`obj[property]`)	Dynamic property names	Yes
Method borrowing (`call/apply`)	Using methods with different context	Yes

Conclusion

Accessing objects through other objects enables data sharing and method reuse. Use direct property access for simple cases, bracket notation for dynamic access, and method borrowing when you need to change the execution context.

AmitDiwan

Updated on: 2026-03-15T23:18:59+05:30

534 Views

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