React Developer Interview Questions

3,481 react developer interview questions shared by candidates

1. const shape = { radius: 10, diameter() { return this.radius * 2; }, perimeter: () => 2 * Math.PI * this.radius, }; console.log(shape.diameter());// console.log(shape.perimeter());//
20 NaN 
let obj = { x: 2, getX: function() { setTimeout(() => console.log('a'), 0);// new Promise( res => res(1)).then(v => console.log(v));// setTimeout(() => console.log('b'), 0);// } } obj.getX();

o/p :- promise , first SetTimeOut and then second SetTimeOut :- 1,a,b



var a = 10; function abc(){ console.log(a);// var a = 20; console.log(a);// } console.log(a);// abc();//


10
10, error can not redeclare a as it is global scoped

10 undefined 20 


var a = {'key': 100}; var b = [] b[a] = 90; console.log(b);//

[object Object]: 90 var a = 50; var b = { name : 'abc' }; function abc(a,b){ console.log(a,b);// b.name = 'cde'; console.log(a,b);// } abc();// abc(a,b);// console.log(a,b);//

50, { name : 'abc' } -> 50, { name : ‘c’de }
50, { name : 'abc' } -> 50, { name : ‘c’de }
50, { name : 'abc' }


undefined undefined undefined undefined 50 { name: 'abc' } 50 { name: 'cde' } 50 { name: 'cde' } 

function foo() { let a = b = 0; a++; return a; } foo(); console.log(typeof a); // console.log(typeof b); //

1
undefined number 

 let a =10 { var a = 20 } console.log(a);//
SyntaxError: Identifier 'a' has already been declared

Sr React Native Developer

Interviewed at Zehn Solutions

2.1
Mar 13, 2025

1. const shape = { radius: 10, diameter() { return this.radius * 2; }, perimeter: () => 2 * Math.PI * this.radius, }; console.log(shape.diameter());// console.log(shape.perimeter());//
20 NaN 
let obj = { x: 2, getX: function() { setTimeout(() => console.log('a'), 0);// new Promise( res => res(1)).then(v => console.log(v));// setTimeout(() => console.log('b'), 0);// } } obj.getX();

o/p :- promise , first SetTimeOut and then second SetTimeOut :- 1,a,b



var a = 10; function abc(){ console.log(a);// var a = 20; console.log(a);// } console.log(a);// abc();//


10
10, error can not redeclare a as it is global scoped

10 undefined 20 


var a = {'key': 100}; var b = [] b[a] = 90; console.log(b);//

[object Object]: 90 var a = 50; var b = { name : 'abc' }; function abc(a,b){ console.log(a,b);// b.name = 'cde'; console.log(a,b);// } abc();// abc(a,b);// console.log(a,b);//

50, { name : 'abc' } -> 50, { name : ‘c’de }
50, { name : 'abc' } -> 50, { name : ‘c’de }
50, { name : 'abc' }


undefined undefined undefined undefined 50 { name: 'abc' } 50 { name: 'cde' } 50 { name: 'cde' } 

function foo() { let a = b = 0; a++; return a; } foo(); console.log(typeof a); // console.log(typeof b); //

1
undefined number 

 let a =10 { var a = 20 } console.log(a);//
SyntaxError: Identifier 'a' has already been declared

Tell me about yourself. Describe yourself in three words. What do you know about this company/organization? How did you hear about this position? Why did you decide to apply for this position? Why do you want to work here? What are your strengths and weaknesses? What is your greatest strength?

React Developer

Interviewed at Anonymous

3.4
Aug 16, 2024

Tell me about yourself. Describe yourself in three words. What do you know about this company/organization? How did you hear about this position? Why did you decide to apply for this position? Why do you want to work here? What are your strengths and weaknesses? What is your greatest strength?

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