Javascript Interview Logic Question

Predict the output:

console.log("20" - 5 + "10");

What is the final output?

var a = "10";
var b = 5;
console.log(a * b + a);

Identify the error (if any):

const a = 10;
{
  const a = 20;
  console.log(a);
}
console.log(a);

What kind of error will occur?

const x;
x = 100;

What will happen?

console.log(b);
var b = 10;

Write logic to swap two numbers

Predict the output

var x = "10";
var x = 10;
console.log(x + 5);

What will be printed?

var a = 5;
if (true) {
  var a = 10;
}
console.log(a);

Will this code run successfully? If yes, what is the output?

var a;
console.log(a);
a = 100;

Write logic to calculate the sum of four numbers using currying.

What is the main difference in return value between forEach and map?

What is the difference in iteration behavior between a normal loop and a for…in loop when an array has missing elements?

Write a program to find the sum of all array elements using reduce.

Write a program to check whether a value exists in an array.

What will be printed?

const arr = [12, "12", 15];
const result = arr.filter((ele) => ele === 12);
console.log(result);

Which loop skips empty elements and why?

const arr = [ , 2, , 4];

How can object values be accessed

What will be the output?

const user = {
  name: "A",
  age: 25,
  age : 32
};
console.log(user.age);

What will be the output?

const obj = {
  info: {
    city: "Ahmedabad"
  }
};
console.log(obj.info2);

What will be the output, if any error then how do handle it?

const obj = {
  info: {
    city: "Ahmedabad"
  }
};
console.log(obj.info2.city);

What will be the output?

const obj = {
  id: 10,
  show: () => {
    return this.id;
  }
};
console.log(obj.show());

Write a program to add new properties to an object.

What will be the output?

localStorage.setItem("count", 10);
localStorage.setItem("count", 20);
console.log(localStorage.getItem("count"));

What will be the output? If any error then how to handle it

localStorage.setItem("user", { name: "A" });
console.log(localStorage.getItem("user"));

What will be the output?

console.log("start");
setTimeout(() => {
  console.log("timeout");
}, 0);
console.log("end");

what is API and to write a API Method with syntax