JavaScript – Tech Talk Guru

Created on April 03, 2022

JavaScript multi choice questions

1 / 10

What’s the output?

const obj = { a: ‘one’, b: ‘two’, a: ‘three’ };
console.log(obj);

{ b: "two", a: "three" }

{ a: "three", b: "two" }

{ a: "one", b: "two" }

SyntaxError

2 / 10

Which of the following methods can be used to display data in some form using Javascript?

document.write()

console.log()

window.alert()

All of above

3 / 10

What’s the output?

!!null;
!!”;
!!1;

false true false

false false true

false true true

true true false

4 / 10

What’s the output?
const numbers = [1, 2, 3];
numbers[10] = 11;
console.log(numbers);

[1, 2, 3, 7 x null, 11]

[1, 2, 3, 11]

SyntaxError

[1, 2, 3, 7 x empty, 11]

5 / 10

Which of the following keywords is used to define a variable in Javascript?

let

var

Both A and B

None of above

6 / 10

How to add new value inside WeakMap ?
const wkMap = new WeakMap();

wkMap.add(‘Jack’, 1);

wkMap.set({name:"Vivek"}, {age:23});

wkMap.addItem(‘Jack’, 1);

wkMap.setItem({name:"Vivek"}, {age:23});

7 / 10

What’s the output?

let number = 0;
console.log(number++);
console.log(++number);
console.log(number);

1 1 2

1 2 2

2 2 2

0 2 2

8 / 10

What’s the output?

let x = 1;
x = (x++, x);
console.log(x);

1

2

Compilation error

undefined

9 / 10

What would be the output of below code?

console.log(num);
let num = 20;

20

ReferenceError

undefined

null

10 / 10

What’s the output?

function getAge(…args) {
console.log(typeof args);
}
getAge(21);

"number"

"object"

"array"

"NaN"

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