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 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?