JavaScript Must Know

This branch is the main JavaScript path.

If you understand these topics well, React and Node.js become much easier.

What this branch covers

• What JavaScript is and where it runs.
• How execution context and call stack work.
• Scope, hoisting, var, let, and const.
• Closures.
• The this keyword.
• Prototypes and prototype chain.
• Arrays, objects, and common transformation methods.
• Event loop.
• Promises and async/await.
• Error handling.
• Modules.
• Debounce and throttle.

How to practice

For each topic:

1. Read the explanation.
2. Write one tiny code example.
3. Predict the output before running it.
4. Explain why the output happened.

JavaScript interviews often test whether you can reason through code, not whether you memorized definitions.