JavaScript while Loop

The while loop repeatedly executes a block of code as long as a given condition is true.

Syntax:

while (condition) {  
  // code block to be executed  
}  

Example:

let loggedIn = false;
let password;
let userName;

while(!loggedIn){  
    userName = window.prompt("Enter your username");  
    password = window.prompt("Enter your password");  

    if(userName === "myuserName" && password === "myPassword"){  
        window.alert("You have logged in");  
        loggedIn = true;  
    }  
    else{  
        window.alert("Wrong credentials");  
    }  
} 

How it works:

Initial setup: loggedIn starts as false, so the while loop will run
Loop condition: while(!loggedIn) means "keep looping while NOT logged in"
User prompts: Each iteration asks for username and password using window.prompt()
Credential check: If both username equals "myuserName" AND password equals "myPassword", it shows success message and sets loggedIn = true
Loop exit: When loggedIn becomes true, the condition !loggedIn becomes false, ending the loop
Wrong credentials: If credentials don't match, it shows "Wrong credentials" and loops again