JAVASCRIPT

javascript default parameters

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

js default parameter

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

js default parameter

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

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

JavaScript Default Parameters

function sum(x = 3, y = 5) {

    // return sum
    return x + y;
}

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

javascript Passing Parameter as Default Values

function sum(x = 1, y = x,  z = x + y) {
    console.log( x + y + z );
}

sum(); // 4

Default Parameter Values in javascript

// Default Parameter Values in javascript
// Longhand:
function volume(l, w, h) {
    if (w === undefined)
      w = 3;
    if (h === undefined)
      h = 4;
    return l * w * h;
  }
console.log(volume(2)); //output: 24
  
// Shorthand:
volume_ = (l, w = 3, h = 4 ) => (l * w * h);
console.log(volume_(2)) //output: 24

javascript Passing Function Value as Default Value

// using a function in default value expression

const sum = () => 15;

const calculate = function( x, y = x * sum() ) {
    return x + y;
}

const result = calculate(10);
console.log(result);            // 160