default argument javascript code example

Example 1: javascript default parameters

function multiply(a, b = 1) {
  return a * b;
}

Example 2: js default parameter

function read_file(file, default_param = false) {
  // Code
}

Example 3: js default parameter

function greeting (name = 'stranger') {
  console.log(`Hello, ${name}!`)
}

greeting('Nick') // Output: Hello, Nick!
greeting() // Output: Hello, stranger!

Example 4: javascript default function parameter value

function multiply(a, b) {
  b = (typeof b !== 'undefined') ?  b : 1
  return a * b
}

Example 5: javascript parameter default parameter

function say(message='Hi') {
    console.log(message);
}
say(); // 'Hi'
say(undefined); // 'Hi'
say('Hello'); // 'Hello'


function date(d = today()) {
    console.log(d);
}
function today() {
    return (new Date()).toLocaleDateString("en-US");
}
date();


function add(x = 1, y = x, z = x + y) {
    return x + y + z;
}
console.log(add()); // 4

Example 6: default value of functin atribute

function say(message='Hi', number=7) {
    console.log(message);
  	console.log(number);
}

say();
// 'Hi'
// 7