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1.What does the following code output?

console.log('1' == 1 && '2' == 2);

undefined

FALSE

null

TRUE

2.What is the purpose of the `String.trimStart()` method in JavaScript?

Adds whitespace to the beginning of a string

Removes whitespace from the beginning of a string

Trims characters from the middle of a string

Converts a string to lowercase

3.How do you convert a string to a date object in JavaScript?

Date.parse(str)

new Date(str)

str.toDate()

new Date.parse(str)

4.What does the `String.slice()` method return if the start index is greater than the end index?

A substring from start index to the end of the string

An empty string

`null`

`undefined`

5.How do you check if a number is an integer in JavaScript?

if (num.isInteger())

num % 1 === 0

Number.isInteger(num)

if (num === Math.floor(num))

6.What is the purpose of the `Object.getOwnPropertyNames()` method in JavaScript?

Returns an array of a given object's own and inherited property names

Returns an array of a given object's own enumerable property names

Returns an array of a given object's values

Returns an array of a given object's own enumerable and non-enumerable property names

7.What does the `String.split()` method return if the separator is not found in the string?

`undefined`

An empty string

`null`

An array with the original string as the only element

8.How do you convert a string to a number with decimals in JavaScript?

parseFloat(str)

Number.parseInt(str)

str.toNumber()

parseInt(str)

9.What is the purpose of the `Number.isNaN()` method in JavaScript?

Determines whether a value is NaN

Returns the square root of a number

Checks if a variable is of type Number

Converts a value to NaN

10.How do you check if a variable is a primitive in JavaScript?

myVar.type === 'primitive'

myVar.isPrimitive()

typeof myVar !== 'object'

myVar instanceof Primitive

11.What does the `Number.MAX_SAFE_INTEGER` property represent in JavaScript?

The largest integer that can be safely represented in JavaScript

The smallest integer that can be safely represented in JavaScript

Infinity

NaN

12.How do you convert a number to a string in JavaScript with a specific base?

String(num, 16)

num.toString(16)

num.toBase(16)

parseInt(num, 16)

13.What is the purpose of the `String.small()` method in JavaScript?

Converts a string to uppercase

Encodes HTML entities

Creates an HTML small element

Trims whitespace from both ends of a string

14.How do you check if an object has a specific property in JavaScript?

if ('propertyName' in myObj)

myObj.hasProperty('propertyName')

if (myObj.propertyName)

if (myObj.hasOwnProperty('propertyName'))

15.What is the purpose of the `Object.keys()` method in JavaScript?

Returns an array of a given object's own and inherited property names

Returns an array of a given object's values

Returns an array of a given object's own enumerable property names

Returns an array of a given object's own enumerable and non-enumerable property names

16.How do you check if a number is positive or negative in JavaScript?

if (num < 0)

if (num.isPositive())

if (num >= 0)

if (num > 0)

17.What is the purpose of the `String.big()` method in JavaScript?

Converts a string to uppercase

Encodes HTML entities

Creates an HTML big element

Trims whitespace from both ends of a string

18.What is the purpose of the `String.fromCharCode()` method in JavaScript?

Trims whitespace from both ends of a string

Reverses the order of characters in a string

Converts a string to lowercase

Returns a string created by using the specified sequence of Unicode values

19.What is the purpose of the `Date.toISOString()` method in JavaScript?

Returns the number of milliseconds since January 1, 1970, 00:00:00 UTC

Returns the current date and time in the local time zone

Returns a string representing a date and time in UTC format

Converts a date to a string in the specified format

20.What will be the value of `result` after the code execution?

var result = (function(x) {
  delete x;
  return x;
})(0);

console.log(result);

undefined

0

null

error

General JS XI