How can I declare and define multiple variables in one statement with JavaScript?

In JavaScript, you can declare and define multiple variables in a single statement by separating them with commas. This approach works with var, let, and const keywords.

Syntax

var variable1 = value1,
    variable2 = value2,
    variable3 = value3;

// Or with let/const
let variable1 = value1,
    variable2 = value2,
    variable3 = value3;

Example: Using var

var firstName = "My First Name is David",
    lastName = "My Last Name is Miller",
    place = "I live in AUS";

console.log(firstName);
console.log(lastName);
console.log(place);

My First Name is David
My Last Name is Miller
I live in AUS

Example: Using let and const

let name = "John",
    age = 25,
    isStudent = true;

const PI = 3.14159,
      GRAVITY = 9.8,
      MAX_SIZE = 100;

console.log(`Name: ${name}, Age: ${age}, Student: ${isStudent}`);
console.log(`PI: ${PI}, Gravity: ${GRAVITY}, Max Size: ${MAX_SIZE}`);

Name: John, Age: 25, Student: true
PI: 3.14159, Gravity: 9.8, Max Size: 100

Mixed Declarations

You can also declare some variables without initial values:

let x = 10,
    y,  // undefined
    z = "hello",
    w;  // undefined

console.log("x:", x);
console.log("y:", y);
console.log("z:", z);
console.log("w:", w);

x: 10
y: undefined
z: hello
w: undefined

Key Points

• Use commas to separate multiple variable declarations
• Works with var, let, and const
• Variables can have different data types in the same statement
• Some variables can be left undefined while others are initialized

Conclusion

Multiple variable declarations in one statement help write cleaner, more concise code. Use this syntax when declaring related variables together, but ensure readability is maintained.