JavaScript Basics: Ternary Operator, Truthy/Falsy, and Switch Case

If you're learning JavaScript, understanding conditionals is very important. In this post, we’ll quickly cover:

• Ternary Operator


• Truthy & Falsy Values


• Switch Case

Let’s keep it simple

Ternary Operator (Short If-Else)

The ternary operator is a short way to write an if...else.

Syntax

condition ? valueIfTrue : valueIfFalse;

Example

let age = 20;



let message = age >= 18 ? "Adult" : "Minor";



console.log(message);

Instead of:

if (age >= 18) {

  message = "Adult";

} else {

  message = "Minor";

}

Use ternary for short and simple conditions only.

Truthy and Falsy in JavaScript:

• In JavaScript, not everything is just true or false.


• Some values are treated as false automatically.

Falsy Values

These are falsy:

false

0

""

null

undefined

NaN

Truthy Examples

"hello"

1

[]

{}

"0"

"false"

Even an empty array [] and empty object{} are truthy!

Example:

if (username) {

  console.log("User exists");

} else {

  console.log("No username");

}

Since "" is falsy, it prints:

No username

Remember: 0 is also falsy!

Switch Case in Javascript:

switch is useful when checking one variable against many values.

let day = "Monday";



switch (day) {

  case "Monday":

    console.log("Start of week");

    break;

  case "Friday":

    console.log("Almost weekend");

    break;

  default:

    console.log("Regular day");

}

Always use break, or the code will continue to the next case.

Quick Summary

• Ternary = short if...else


• Falsy values: false, 0, "", null, undefined, NaN


• Switch is great for multiple fixed values


• Don’t forget break in switch