Unlock the Power of Default Parameters in JavaScript

A Game-Changer in Functionality

Starting from JavaScript ES6, a revolutionary feature has taken the coding world by storm – default parameters for functions. This innovative feature allows developers to provide default values for function parameters, which are used when the function is called without passing the corresponding arguments.

Default Parameters in Action

Let’s dive into a simple example to illustrate the concept. Consider a greet() function with a default parameter name set to “Guest”. When we call the function without passing any argument, it uses the default value.

function greet(name = "Guest") {
  console.log(`Welcome, ${name}!`);
}

greet(); // Output: Welcome, Guest!

Multiple Scenarios, One Solution

But what happens when we pass arguments to the function? Let’s explore three scenarios:

• Both arguments passed: sum(5, 15) – x takes 5, and y takes 15.
• One argument passed: sum(7) – x takes 7, and y takes the default value 5.
• No arguments passed: sum() – x and y take the default values 3 and 5, respectively.

function sum(x = 3, y = 5) {
  return x + y;
}

console.log(sum(5, 15)); // Output: 20
console.log(sum(7)); // Output: 12
console.log(sum()); // Output: 8

Dynamic Default Values

In JavaScript, you can take default parameters to the next level by passing one parameter as the default value for another. For instance, consider a sum() function where:

• The default value of x is 1.
• The default value of y is set to the x parameter.
• The default value of z is the sum of x and y.

function sum(x = 1, y = x, z = x + y) {
  return x + y + z;
}

console.log(sum()); // Output: 4

Functions as Default Values

But that’s not all. You can even pass a function as a default value in JavaScript. Imagine a calculate() function where:

• 10 is passed to the function.
• x becomes 10, and y becomes 150 (the sum() function returns 15).
• The result? A staggering 160!

function sum(x = 3, y = 5) {
  return x + y;
}

function calculate(x = 10, y = sum(x, 5)) {
  return x + y;
}

console.log(calculate()); // Output: 160

The Power of Undefined

In JavaScript, when you pass undefined to a default parameter function, the function takes the default value. This feature opens up new possibilities for coding flexibility and creativity.

function greet(name = "Guest") {
  console.log(`Welcome, ${name}!`);
}

greet(undefined); // Output: Welcome, Guest!

With default parameters, you can write more efficient, flexible, and powerful code. Master this feature, and unlock a world of possibilities in JavaScript development.