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Questions and Answers
What is the purpose of the 'this' keyword in JavaScript?
What is the purpose of the 'this' keyword in JavaScript?
What is the difference between 'var' and 'let' keywords in JavaScript?
What is the difference between 'var' and 'let' keywords in JavaScript?
What is the purpose of the 'prototype' property in JavaScript?
What is the purpose of the 'prototype' property in JavaScript?
What is the difference between 'null' and 'undefined' in JavaScript?
What is the difference between 'null' and 'undefined' in JavaScript?
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What is the purpose of the 'bind' method in JavaScript?
What is the purpose of the 'bind' method in JavaScript?
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In JavaScript, what happens when you use the 'delete' operator on a property?
In JavaScript, what happens when you use the 'delete' operator on a property?
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What is the purpose of the 'call' method in JavaScript?
What is the purpose of the 'call' method in JavaScript?
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What happens when you try to access a non-existent property in JavaScript?
What happens when you try to access a non-existent property in JavaScript?
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What is the purpose of the 'apply' method in JavaScript?
What is the purpose of the 'apply' method in JavaScript?
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What is the purpose of the 'arguments' object in JavaScript?
What is the purpose of the 'arguments' object in JavaScript?
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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, whereaslet
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, whereasundefined
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 boundthis
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!