Senior Level JavaScript Interview Questions — Part 1 🎓🚀

Are you preparing for a senior JavaScript role? You’ll need to be ready for advanced questions that test your understanding of JavaScript beyond just syntax. This guide dives into real-world problems and concepts every senior developer should know. Let’s get you interview-ready with 10–15 questions and their answers! 💼✨

1. What’s the difference between == and === in JavaScript? When would you use each? 🤔

Answer:

• == (loose equality) compares values for equality, allowing for type coercion, so 2 == "2" is true.
• === (strict equality) compares both value and type, so 2 === "2" is false.
• Use === when exact type matching is required, which is preferred in most cases to avoid unexpected type coercion.

2. Explain this in JavaScript and give an example of how it can be used differently in different contexts. 🎯

Answer:

• In JavaScript, this refers to the context in which a function is called. For example:
• Global scope: this refers to the global object (e.g., window in browsers).