Q Consider the following JavaScript function to change the
color of the text box named txtName:
Function color(col) {
document.forms[0].txtName.style.background = col
}
Which of the following will change the color of the text box
to green, as long as user is pressing a key?
<input
type="text" onkeypress="color('green')"
onkeyup="color('white')" name="txtName"/>
Q Consider three variables:
var someText = 'JavaScript1.2';
var pattern = /(\w+)(\d)\.(\d)/i;
var outCome = pattern.exec(someText);
What does pattern.ignoreCase contain?
True
Q What kind of function is function* in JavaScript? (Choose
all that apply)
It is a
function which can return value several times
Q When toggling a variable. Its cycle must be 0 and 1. When
the variable’s active is 0, the next value should be 1, and when the variable’s
active value is 1, the next value should be 0.
Considering the scenario above, which of the following is
correct?
Q=1-q
Q Which of the following code snippets shows the correct way
to detect an array that does not contain a specific value.
var aVar
=["Banana","Orange","Apple","Mango"];
var bVar =
aVar.indexOf("Orange");
If(bVar ==
-1)
{
//
requirement
}
Fruits
variable does not exist so considering it aVar
Q Which of the following will change the color of paragraph’s
text to blue when a user hovers over it, and reset it back to black when the
user hovers out?
<p
onmouseover=”style.color=’blue'” onmouseout=»style.color=’black'»> The text
of the paragraph..</p>
Q Which of the
following choices will turn a string into a JavaScript function call (case with
objects) of the following code snippet?
<script>
window.foo = {
bar: {
baz: function() {
alert(‘Hello!’);
}
}
};
</script>
window.foo = {
bar: {
baz: function() {
alert(‘Hello!’);
}
}
};
</script>
window['foo']['bar']['baz']();
Q What will be
logged in the console?
let a ={['foo_' +
(() => 1)()]:2};
console.log(a);
{foo_1: 2}
Q Consider the
following code snippet:
<form
name="frmOne">
<select
name="selList" size="1" onChange="change()">
<option
value="http://www.hotmail.com">tHotmail</option>
<option
value="http://www.yahoo.com">tHotmail</option>
</select>
</form>
Considering that
when option button is selected , the appropriate website should be opened
immediately, what should the change() function look like?
location = document.frmOne.selList.options[document.frmOne.selList.selectedIndex].value;
Q Which of the
following will check whether the variable vRast exists or not?
if(typeof vRast =="undefined")
Q Which of the
following is the correct way to stop setInterval() from calling a function in
Javascript?
Q what will be
written in the alert box after executing the following code?
var a=5;
var b =1;
if(!!"false")
{
a =a+5;
b=3
}
if(!!0)
{
a =a+5;
b = b+2;
}
console.log(a+b);
13
Q What kind of array
representation of the pixels does Canvas ImageData return when you call
Imagedata.data?
Uint32Array
Q what do JS classes
support?
None, JS has prototype chain instead of classes
Q What is the output
of following code?
if(typeof(Storage) !== "undefined") {
localStorage.age =5;
sessionStorage.age = 5;
alert(localStorage.age
+ sessionStorage.age);
}
else
{
alert("Sorry, your browser does not support web
storage");
}
55
Q What is true about strict mode? (Choose all that apply)
It
applies to individual functions
It
apples to entire script
Q Which of the
following code snippets changes an image on the page?
Var img
= document.getElementById(“imageid”);
Img.src
= “newimage.gif”;
Q what is the output of the following code?
Var foo = 123e5;
Var bar = 10;
Var foobar = foo + bar;
12300010
A form contains two fields named id1 and
id2. How can you copy the value of the id2 field to id1?
a.
document.forms[0].id1.value=document.forms[0].id2.value
b. document.forms[0].id2.value=document.forms[0].id1.value
c.
document.id1.value=document.id2.value
d.
document.id2.value=document.id1.value
Q Which of the following is not a valid string
method?
a. link()
b. italics()
c. str()
d. sup()
Q Which of the
following code samples creates an alert box with "false" in it.
var n =3.2;
alert(n % 1 === 0);
Q what is Promise?
Async call
Q which event
handlers can be used to create hover effect on HTML element?
OnMouseover and onMouseOut
Q what does ~ mean
in bitwise operation javascript
NOT
Q What will be
returned if we call f(3)?
const f = (x,y =
true) => x * y;
3
Q What will be the
value of s.size after executing this code?
let s = new Set();
s.add('aa').add('bb').add('cc').add('aa').add('bb');
3
Q What is true about
an Array?
This code can be used to create an array let a = []; a[10.5] =
"Hey";
This code can be used to create an array let a = new
Array("Hey",10.5);
Q what are valid
states of the created Promise?
Following are the
valid states in promise:
- Pending – not yet resolved
- Succeeded / Fulfilled – pending
operation succeeded
- Failed / Rejected – pending operation
failed
Answer is:
Pending, Fulfilled, Rejected
Q Which function
will return 10 when called like this : f(10)
const f = (...f) => f.reduce(f =>f);
const dJ = dJ => dJ;
Q Which of the
following are the valid JavaScript code to obtain the number of milliseconds
since the epoch? (Check all that apply)
var timestamp = new Date().getTime();
var timestamp = Number(new Date());
var timestamp = new Date().valueOf();
Q what will be the
output of the following code?
var x = [typeof x,
typeof y][1];
console.log(typeof
typeof x);
string
Q What is
JavaScript?
It’s the programming language used by only web developers
Q Which of the following determines whether
cookies are enabled in browser or not ?
(navigator.cookieEnabled)? true: false;
Q Which are the
correct ways to redirect to a URL in JavaScript?
window.location
= "http://www.foobar.com";
window.location.assign("http://www.foobar.com");
Q how can you remove spaces, tabs and line terminator
characters around the string? String is defined like this let string = ‘ hey ’;
string =
string.trim();
Q How can you get type of the variable
Using type
of operator
Q Given a p element with some text content, which of the
following code snippets sets the background color of the text to yellow, its
color to red and its font size to 20px?
var p =
document.getElementById("demo1");
p.setAttribute("style","background-color:yellow;color:red;font-size:20px");
Q How many yield keywords can be used in function*
functions?
As many as
needed
Q what does let mean in JavaScript?
It is used
to create local block scoped variables
Q which statement about Promises is not correct?
Promise may
never resolve value
It’s possible to test which promise resolves first with
method from Promise object (chaining promise)
All
Promises will eventually resolve or reject
Q promise is created. When will it resolve?
Immediately
In the feature
Never
UnKnown
Q The following are
sample codes on how to merge properties of two JavaScript objects dynamically:
var obj1 = {food: 'pizza', car: 'ford'};
var obj2 = {animal :'dog'};
Function
MergeRecursive(obj1,obj2)
{
var obj3 =
{};
for(var
attrname in obj1){ obj3[attrname] = obj1[attrname]}
for(var
attrname in obj2){ obj3[attrname] = obj2[attrname]}
}
Q What does a “for…in” loop do?
It iterates
over the enumerable properties of an object, in arbitrary order.
Note: The for...in statement iterates over
the enumerable
properties of an object, in original insertion order. For each
distinct property, statements can be executed.
Here in options each answer is given with arbitrary order.
Q how often will message “hey” be logged in console?
setInterval(() => {console.log('hey'),1});
Every 1
milliseconds
Q Which statement is correct about null and undefined?
Undefined
indicates that a variable is not defined in the scope. Null can be assigned to
a variable as a representation of no value.
Q Which function determine whether the beginning of the
param1 instance matches the param2?
function abc(para1,para2)
{
return para1.indexOf(para2) == 0;
}
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