Junior JavaScript Developer Interview Flashcards

Number, String, Boolean, Null, Undefined, Object, Symbol, BigInt.

• var: function-scoped, can be redeclared and updated.
• let: block-scoped, can be updated but not redeclared in the same scope.
• const: block-scoped, cannot be updated or redeclared.

A closure is a function that remembers and accesses variables from its outer scope even after that outer function has finished executing.

Arrow functions have a shorter syntax and do not have their own this, arguments, or super. They inherit this from their surrounding context.

Event bubbling is the process where an event starts from the deepest target element and then propagates up to its ancestors in the DOM tree.

• Using object literal: { key: value }
• Using constructor: new Object()
• Using Object.create() method.

• == compares values with type coercion.
• === compares values without type coercion (strict equality).

Hoisting is JavaScript's behavior of moving declarations (var, function) to the top of their scope before code execution.

this refers to the object that is executing the current function. It varies based on how the function is called.

Promises represent the eventual completion (or failure) of an asynchronous operation and its resulting value.

• Synchronous code runs sequentially, blocking the thread until finished.
• Asynchronous code runs independently, allowing other code to run while waiting.

The Document Object Model (DOM) is a programming interface for HTML and XML documents, representing the page so scripts can change the document structure, style, and content.

Using try...catch blocks, and optionally finally to run code regardless of error.

• null is an assigned value meaning "no value".
• undefined means a variable has been declared but not assigned a value.

map() creates a new array by applying a function to each element of the original array.