Why should you care?

When a user logs in, you store their name in a variable and show it on every page. When the price changes, you update one variable instead of hunting through the whole file.

See it live — copy this example

Paste into an HTML file or the browser console (F12). Use Run below when the live editor is available.

let userName = "Priya";
const maxLoginAttempts = 3;
let score = 10;
score = score + 5;
console.log(userName, score, maxLoginAttempts);

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

What happened?

• let means the value can change later.
• const means you will not reassign the variable (the name stays fixed).
• userName and score are let; maxLoginAttempts is const.

Practice next

1. Run the example in the browser console.
2. Change userName to your name and run again.
3. Increment score several times with score = score + 1.
4. Swap let for const on score and see which assignments fail.
5. Add a boolean isLoggedIn variable and log it with the others.

Remember

let = value can change const = binding stays fixed Give variables clear names like userName

ScriptVerse user session

After login, the app stores displayName and role in variables used across navbar, profile, and admin panels.

Outcome: One source of truth for user state avoids repeating API calls on every component.