Interview Q&A / JavaScript

1. How do tasks and microtasks work in the JavaScript event loop?

   JavaScript runs one piece of code at a time. After the current code finishes, it runs all waiting microtasks (like promise callbacks) before the next task (like a setTimeout callback).

   IntermediateIn-depth2 min read
2. How does the this keyword work in JavaScript?

   this is decided by how a function is called, not where it is written. A method call obj.fn() sets this to obj; new sets it to the new object; call, apply and bind set it explicitly; a plain call gives undefined in strict mode. Arrow functions have no own this and use the surrounding one.

   IntermediateIn-depth3 min read
3. What is the difference between debounce and throttle? Implement both.

   Debounce waits until calls stop for a set time and then runs the function once, like search-as-you-type. Throttle runs the function at most once per time window no matter how often it is called, like handling scroll events. Both are built with a closure that holds a timer or a timestamp.

   IntermediateIn-depthCoding3 min read