Javascript Datatypes and Variables(Kushal Das)

In Replit, we have created a file named “DemoFile.js”, which command is used to run the JavaScript code within it.

• run DemoFile

• run DemoFile.js

• node DemoFile

• node DemoFile.js

Answer explanation

Answer Explanation :

On Replit, click the shell tab on the right. Effectively this gives you a terminal and access to node.js. 

node <file name>  is the command to get node to run your program, in our case file name is “DemoFile.js”.  

Please note: DemoFile.jsand DemoFile are two different files.

JavaScript can be used for?

• Creating web pages

• Game Development

• Building web servers

• All of the Above

Answer explanation

You can use JavaScript for multiple purposes like creating web pages, game development, building web servers, etc.

JavaScript is ________________ typed language.

• Statically

• Dynamically

• Strongly

• None of the Above

Answer explanation

JavaScript is a dynamically-typed language where the interpreter assigns variables a type at runtime based on the variable's value at the time.

This means below code snippet is valid in JavaScript:

let num = 1;
num = "some string";

Which of the following is not a data type?

• String

• null

• number

• char

Answer explanation

In JavaScript, char is not a data type.

___________ data type is used to represent the intentional absence of any value.

• undefined

• boolean

• null

• None of the Above

Answer explanation

null used for intentionally missing values.

What will be the output of the below code snippet:

var num;
console.log(num);

• null

• undefined

• number

• string

Answer explanation

Variable num is only declared not assigned any value hence the output will be undefined.

Which is the correct statement for declaring a variable "myName" with its initial value as “Kushal”? (Camel Case)

• var

  myName="Kushal";

• var myname="Kushal";

• var MyName="Kushal";

• All of the above

Answer explanation

JavaScript is a case-sensitive language. This means that capitalisation matters. Variable myName is not the same as MyName nor myname. It is possible to have multiple distinct variables with the same name but different casing.

Which of the following is a valid variable name?

• 1var 1_Name;

• var @_Name

• var _Name

• All of the above

Answer explanation

A variable name can start with a letter, underscore (“_”), or dollar sign (“$”). After the first letter, you can use number, letter, underscore, and dollar sign.

Best practice to declare a variable.

• var firstname

• var Firstname

• var firstName

• var FirstName

Answer explanation

The best practice is to write variable names in camelCase. In camelCase, multi-word variable names have the first word in lowercase and the first letter of each subsequent word is capitalised.

What will be the output of the below code snippet:

var number = 10;
number = "hello";
console.log(number);

• 10

• hello

• 10hello

• None of the above

Answer explanation

Variable number was assigned 10, later we reassigned “hello” to it. Since the number is declared using the var keyword we can re-assign the value.