JavaScript Fundamentals Quiz

10 Questions

What is the purpose of the 'this' keyword in JavaScript?

To refer to the current object

What is the difference between 'var' and 'let' keywords in JavaScript?

Var is used for function scope and let is used for block scope

What is the purpose of the 'prototype' property in JavaScript?

To inherit properties from another object

What is the difference between 'null' and 'undefined' in JavaScript?

Null is used to represent an empty value and undefined is used to represent an uninitialized variable

What is the purpose of the 'bind' method in JavaScript?

To call a function with a specific context

In JavaScript, what happens when you use the 'delete' operator on a property?

It removes the property from the object

What is the purpose of the 'call' method in JavaScript?

To call a function with a different 'this' context

What happens when you try to access a non-existent property in JavaScript?

It returns undefined

What is the purpose of the 'apply' method in JavaScript?

To call a function with an array of arguments

What is the purpose of the 'arguments' object in JavaScript?

To access the parameters of a function

Study Notes

JavaScript Key Concepts

The this keyword in JavaScript refers to the current execution context of the function, allowing it to dynamically change its value based on how the function is called.

Variable Declarations

var keyword declares a variable that is scoped to the nearest function block, allowing it to be re-declared and updated within its scope, whereas let keyword declares a variable that is block-scoped, meaning it cannot be re-declared within its scope.

Object-Oriented Programming

The prototype property in JavaScript is used to create a new object that inherits properties and behavior from an existing object, allowing for inheritance and polymorphism.

Data Types

null represents the intentional absence of any object value, whereas undefined represents an uninitialized or non-existent variable or property.

Function Binding

The bind method in JavaScript creates a new function that has the same function body as the original function, but with a bound this context, allowing it to be called with a specific context.