Javascript Programming Quiz

1. When you invoke the........ method on a function f and pass an object o, the method returns a new function.

apply()
call()
bind()
string()

2. What will be printed in the console on execution of the following JS code:

var array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];

var myArr= array.filter(v => v % 3 === 0);



console.log(myArr);

myArr
[3, 6, 9, 12, 15]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
[1, 2, 4, 5, 7, 8, 10, 11, 13, 14]

3. If var A={B:3, C:5}, how to use the delete operator to delete one of the properties of an object.

delete
delete A
delete A.B
delete A[0]

4. What will be the output of the below code ?

var package;

console.log("Package: " + package)

console.log("Amount: " + amount);

Package: null; Amount: null;
Package: undefined; Amount: undefined;
Package: null; An ReferenceError is thrown saying amount is not defined;
Package: undefined; An ReferenceError is thrown saying amount is not defined;

5. Which object is the top of the hierarchy?

Form Control Elements
Document Object
Form Object
Window Object

6. What will be the output of the following JavaScript code?

function myfun()
 
{

  var a = null;

   document.getElementById ("demo").innerHTML = Boolean(a);

}
}

true
false
error
undefined

7. What is the code required to delete all “weight” tags?

delete weight(pt).all;
delete pt.element[all];
delete pt;
delete pt..weight;

8. What will be the output of the following JavaScript code?

< p id="demo">< /p>

< script>

var a = 20;

var b = "30";

var c = a + b;

document.getElementById ("demo").innerHTML = c;

< /script>

50
20+30
2030
error

9. Which of the following is the descendant operator?

..
...
*
@

10. What is the code to be used to trim whitespaces?

let trimmed = (l.trim() for (l in lines));
let trimmed = (trim(l));
let trimmed = l.trim();
let trimmed = for(l in lines));