Javascript Questions

NaN property is a property of the global object that is used to represent the Not-a-Number value.

Number object is used to perform number operations.

Boolean object is used to perform boolean operations.

Falsy values are:

• 0
• ''
• null
• undefined
• NaN
• false

JavaScript data types are the types of values that JavaScript can store.

There are seven data types in JavaScript:

• Number
• String
• Boolean
• Undefined
• Null
• Symbol
• Object

The push method is used to add an element to the end of an array.

The window object is a global object that has the properties pertaining to the current DOM document

The document property of the window object has the DOM document and associated nodes and methods that we can use to manipulate the DOM nodes and listen to events for each node.

The window object is global, so it’s available in every part of the application.

JavaScript is a programming language that allows you to write applications that can run on the client side or server side

Undefined is a value that JavaScript assigns to variables that have not been assigned a value.

Null is a value that JavaScript assigns to variables that have been assigned a value but that value is null.

The === operator is used to compare two values and types. It returns true if both values and types are equal, and false if they are not equal.

There are three looping structures in JavaScript:

• For Loop
• While Loop
• Do While Loop

Break and continue statements are used to exit a loop or switch statement.

Break is used to exit a loop

Continue is used to skip the current iteration and continue to the next iteration.

There are three boolean operators in JavaScript:

• &&
• ||
• !

In Pass by value, function is called by directly passing the value of the variable as an argument. So any changes made inside the function does not affect the original value.

In Pass by Reference, Function is called by directly passing the reference/address of the variable as an argument. So changing the value inside the function also change the original value. In JavaScript array and Object follows pass by reference property.

The prototype is an object that is associated with every functions and objects by default in JavaScript, where function's prototype property is accessible and modifiable and object's prototype property is not visible

A callback is a function passed into another function as an argument, which is then invoked inside the outer function to complete some kind of routine or action.

A constructor is a special function that creates and initializes an object instance of a class. The purpose of a constructor is to create a new object and set values for any existing object properties.

The Document Object Model (DOM) is an API for HTML and XML documents. It is the programming interface for the HTML and XML documents.

Arrow functions are a new syntactic construct in JavaScript. They are a shorter way to write function expressions.