JavaScript Fundamentals Quiz
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Questions and Answers

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

  • To refer to the previous object
  • To refer to the global object
  • To refer to the current object (correct)
  • To refer to the parent 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 (correct)
  • Var is used for global variables and let is used for local variables
  • Var is used for local variables and let is used for global variables
  • Var is used for block scope and let is used for function scope
  • What is the purpose of the 'prototype' property in JavaScript?

  • To inherit properties from another object (correct)
  • To delete a property from an object
  • To create a new object
  • To add a new property to an object
  • What is the difference between 'null' and 'undefined' in JavaScript?

    <p>Null is used to represent an empty value and undefined is used to represent an uninitialized variable</p> Signup and view all the answers

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

    <p>To call a function with a specific context</p> Signup and view all the answers

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

    <p>It removes the property from the object</p> Signup and view all the answers

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

    <p>To call a function with a different 'this' context</p> Signup and view all the answers

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

    <p>It returns undefined</p> Signup and view all the answers

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

    <p>To call a function with an array of arguments</p> Signup and view all the answers

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

    <p>To access the parameters of a function</p> Signup and view all the answers

    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.

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    Description

    Test your knowledge of basic JavaScript concepts, including 'this', 'var', 'let', 'prototype', 'null', 'undefined', and 'bind'. Prepare for your JavaScript interview!

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