If/Else & Truthy/Falsy

Branch logic (IF) in JavaScript is very commonly used.

If / Else

main.js

const score = 85;
if (score >= 90) {
  console.log("Grade A");
} else if (score >= 80) {
  console.log("Grade B");
} else {
  console.log("Grade C");
}

Truthy & Falsy Values

In addition to pure true/false values, JS considers all values as "Truthy" (considered true when put into an IF check), EXCEPT THESE 6 ELEMENTS:

1. false

2. 0

3. "" (Empty string)

4. null

5. undefined

6. NaN (Not a Number)

main.js

let userName = ""; // Empty string
if (userName) {
    console.log("Hello " + userName);
} else {
    // Forced into ELSE because an empty string is considered 'Falsy'.
    console.log("Please enter your name!");
}