OBJECTIVES TYPE QUESTIONS
1. Fill in the Blanks:
a. The alert box is used to displays information to the
user.
b. A variable is a storage area where value is stored
and retrieve when required.
c. The modulus operator finds out the remainder.
d. The ! (exclamation mark) operator is a unary operator.
e. The conditional operator uses ? (question mark) and : (colon) characters.
2. Write TRUE or FALSE.
a. The
semi colon at the end of simple statement in Java Script is mandatory. FALSE
b. In Java
Script MARKS and marks are treated as the same variable. FALSE
c. A
simple statement must be enclosed in braces. TRUE
d. A
compound statement consist of several instructions grouped in a block. TRUE
e. The switch statement can only be used to compare an expression against constant. TRUE
3. Multiple Choice Questions:
a. Which
one is a valid name in JavaScript.
1employeename
b. A
block of statement is enclosed within.
{
} ( curly Braces)
c. The
statement used to exit from the switch…. case statement is
exit
d. ___
takes a number as input from the user.
Prompt
dialog box
e. Which
one of these is not an arithmetic operator in JavaScript.
/
(backward Slash)
f. ==is
a/an
Relational
Operator.
DESCRIPTIVE TYPE QUESTIONS
1. Short answer questions:
a. What
are the three data types in JavaScript?
The
three data type in JavaScript are:
i. Number Eg: 56, 45.12 etc.
ii. String Eg: “Grade” etc
iii. Boolean Eg: True or False.
b. How
will you declare variables sub1, sub2, and sub3 in JavaScript?
We can
declare variables sub1, sub2 and sub3 in JavaScript as:
var sub1, sub2, sub3;
c. Name
the different form of if statement.
The
different form of if statement is:
i. if statement
ii. if… else statement
iii. if… else if statement
d. Name
the three logical operators.
The
three logical operators are:
i. && (AND) operator
ii. ||(OR) operator
iii. ! (NOT) operator
e. Write
the statement equivalent to A++ and A--.
The
statements equivalent to A++ and A- - are:
i. Increment Operator
ii. Decrement Operator
f. Write
the short hand form for the following.
A = A + 15
B = B + 1
A+=15
B+=1
2. Long answer question:
a.
Explain the two types of comments in JavaScript.
Comment
mean not executable statement or ignore statement.
The two
types of comments in JavaScript are:
i) Single line comment: A
comment which is restricted to only a single line. It always starts with a pair
of (//) backward slash. The browser ignores anything typed from the pair of slash
(//) till the end of the same line. Example: // single line comment.
ii)
Multi line comment: A comment which is
applicable to one or more statements. It always indicates with a (/*) backward
slash asterisk and (*/) asterisk backward slash. The browser ignores the
statements between these characters. It is also known as a block comment:
Example: /*This is block comment known as multi line comment */.
b. What
are the rules for naming the JavaScript variables?
The
rules for naming the JavaScript variables are given below:
i) In JavaScript a variable may include only letter A to Z, a to z, 0 to
9, the dollar symbol $, and the _ underscore.
ii) No other characters such as a space, or punctuation are allowed in a
variable name.
iii) The first character of variable name can be only a to z, A to Z and
_ underscore ( no number)
iv) Name are case sensitive
v) There is no set limit on variable names length.
vi) You must declare the JavaScript variable with the var keyword.
c. What
are the limitation of the switch statement?
The
limitations of a switch statement are:
i) The case label cannot be a variable. Example: case n: where n is a
variable.
ii) the case label cannot be a range. Example: case (1.3):. This is not
a valid content.
d. What
is the different between simple and compound statements?
The
differences between simple and compound statement is that:
A simple statement consists of a single instruction ending with a semi
colon (;). It does not required braces to enclosed it. Whereas,
A compound statement consists of several instructions grouped in a block.
It must be enclosed in braces if we wish to treat them all as a single
statement.
e.
Explain the working of conditional operators with an example.
The conditional
(ternary) operator is the only JavaScript operator that takes three operands.
A condition followed by a
question mark (?), then an expression to execute if the condition is true followed
by a colon (:), and finally the expression to execute if the condition is false.
This operator is frequently used as a shortcut for the if statement.
Example:
Below is the code finding the age below 18 or above 18
years using the conditional operators.
<!DOCTYPE
html>
<html>
<head>
</head>
<body>
<script>
var
age, result;
age
= 20
result
= age > 18 ? “You are over 18 year”
: “You are below or equal to 18 years”
document.write
(result)
</script>
</body>
</html>
APPLCATION BASED QUESTIONS:
1. Jasmin
has written the given code to display a message box on the screen, but the
message box is not showing on the screen. Find the problem in this code and
rewrite it to display the given statement in a message box.
|
<!DOCTYPE html> <html> <body> <script language = “javascript” type
= “text/javascript”> alert(“This is my first JavaScript Code”) </script> </body> </html> |
2. Rewrite
the following code using if…..else if statement.
switch (direction)
{
case “N” : a = “north” ; break;
case “E” : a = “north” ; break;
case “W” : a = “north” ; break;
case “S” : a = “north” ; break;
default : a = “Enter correct code”;
}
document.write (a)
|
if (direction = = “N”) a= “North” else if (direction = = “E”) a= “East” else if (direction = = “W”) a= “West” else if (direction = = “S”) a= “South” else a = “Enter correct code” |
3. What will
be the output of the following code:
var a, b
a= 5
b = 10
b+=a
a++
b- -
document.write(“a =” + a + “<br/>”)
document.write(“b =” + b )
|
Given, a= 5 b
= 10 to find the var a, b= ? Given, b+=a Therefore, b = b+ a (According
to Compound assignment operator+= it
adds the right-side operand to the left side and assign the result to the
left side operand.) So, we got, b = 10 + 5 = 15 ( now the value in b = 15) Again, given a++ Therefore, a = a + 1 (According to increment operator ++ it increases
the value stored in a variable by one.) So, we got a = a+1 = 6 (now the value in a = 6) Lastly Given b- - Therefore b = b - 1 (According to decrement operator - - it
decreases the value stored in a variable by one.) So, we got b = 15 – 1 = 14 (now the value in b = 14) So, we get the output a = 6 b = 14 |
4. Evaluate
the following expression and find out its output, assuming b = 4 and c = 4
a = b *
3 / 4 + c / 4 + 8 – b + 5 / 8
Answer
|
Solution a = b * 3 / 4 + c / 4 + 8 – b + 5 / 8 Now putting the value of b and c we
get a = b * 3/4 + c/4 + 8 – b + 5/8
= 4 * 3/4 + 4/4 + 8 – 4 + 5/8
= 12/4 + 4/4 + 8 – 4 + 5/8
= 3 + 1 + 8 – 4 + 0.625
= 12.625-4
= 8.625 Note: Solve every Mathematical
Question using Arithmetic Operator Procedure. |
5. Assuming
A = 5 and B = 6, what will be the result of the following statements:
i. ((A
!= B) && (A >=B))
ii. ((A
!= B) || (A <= B))
iii) ! (A
> B)
Answer
|
i. false Explanation: Given, (A != B) and then putting the values of A and B, we get, (5 != 6), means 5 is
not equal to 6 , which is true. Again, (A >= B) and then putting the values of A and B, we get, (5 >= 6), means 5 is greater
than or equal to 6, which is false. And, ((A != B) && (A >=B)), Contains logical operator &&
(AND). So According to && (AND) logical operator, if the both
conditions (A != B), (A >= B) is true then only the result will be
true, otherwise false. So, the final result in this case will be false.
ii. true Explanation: Given, (A != B) and then putting the values of A and B, we get, (5 != 6), means 5 is
not equal to 6 , which is true. Again, (A <= B) and then putting the values of A and B,
we get, (5 <= 6), means 5 is less than or equal to 6, which is true. And, ((A != B) || (A <=B)), Contains logical operator || (OR). So According
to || (OR) logical operator, if the both conditions (A != B), (A >= B) is
false then only the result will be false, otherwise true. So, the final result in this case will be true.
iii. true Explanation: Given, (A > B) and then putting the values of A and B,
we get, (5 > 6), means 5 is greater than 6, which is false. And, !(A > B) Contains logical operator ! (NOT). So According
to ! (NOT) logical operator, if the conditions (A > B) is true the result will be false, and if the condition is false the
result will be true, in vice versa. So, the final result in this case will be true for
the condition is false. |
6. Write
the following if…. else statement using the conditional operator:
if (x =
= 100)
a = “x
is 100”
else
a = “x is not 100”
Answer
|
a = x == 100 ? “x is 100” : “x is not 100” (answer) Explanation: Since the general format of if… else statement for
the given statement is: if (x ==100) { document.write(“x is 100”) } else { document.write(“x is not 100”) } So, relating this format with the question we get, condition
= (x==100). We need to write the using conditional operator. So, the general
format of conditional format is given below:
var x = 100; x = x == 100? "x is
100": "x is not 100" document.write( x); The out put we get here is x is 100 as it has
executed the true part, for in x the value is assign 100 and the condition we
gave is x= x==100. so the final result we got using conditional operator
a = x == 100 ? “x is 100” : “x is not 100” is x is 100.
|
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