Default Parameters
Default parameters allow us to provide fallback values for function parameters in case no value or undefined is passed when the function is called.
Syntax
To define a default parameter, we can assign a value directly to the function parameter in the function declaration.
JAVASCRIPT
1function functionName(parameter = defaultValue) {
2 // function logic
3}Examples
Let's take a look at some examples of using default parameters:
Example 1:
JAVASCRIPT
1function greet(name = 'friend') {
2 console.log(`Hello, ${name}!`);
3}
4
5// Output: Hello, friend!Example 2:
JAVASCRIPT
1function multiply(a, b = 1) {
2 return a * b;
3}
4
5// Output: multiply(5) => 5Example 3:
JAVASCRIPT
1function fetchUserData(username, timeout = 5000) {
2 // logic to fetch user data
3}
4
5// Output: fetchUserData('john_doe')Example 4:
JAVASCRIPT
1function calculateArea(radius = 1) {
2 return Math.PI * radius * radius;
3}
4
5// Output: calculateArea()Example 5:
JAVASCRIPT
1class Rectangle {
2 constructor(width = 1, height = 1) {
3 this.width = width;
4 this.height = height;
5 }
6}
7
8// Output: new Rectangle()Example 6:
JAVASCRIPT
1const getHeroes = (team = 'Lakers') => {
2 // logic to get list of heroes
3};
4
5// Output: getHeroes()xxxxxxxxxx32
};// Example 1function greet(name = 'friend') { console.log(`Hello, ${name}!`);}// Example 2function multiply(a, b = 1) { return a * b;}// Example 3function fetchUserData(username, timeout = 5000) { // logic to fetch user data}// Example 4function calculateArea(radius = 1) { return Math.PI * radius * radius;}// Example 5class Rectangle { constructor(width = 1, height = 1) { this.width = width; this.height = height; }}// Example 6OUTPUT
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