Javascript conditional statements 1

JavaScript if...else Statements

REVIEW
<html>
<body>
<script>
var x= prompt("Who created the JavaScript? "," ");
var y= "Brendan Eich", n= "brendan eich", m=
"Brendan"
var z= (x==y||x==n||x==m)?"Correct": "Wrong";
alert(""+z+"");
document.write("Correct Answer: "+y+"");
</script>

Identify if correct or error source code
If error ,find code/s or missing codes that will cause error.

7. var x= prompt(What is kbps stand for? “ ,””);

8. Var y= “kilobytes per seconds”

9. var z= (x==y) Correct: Wrong ;

10. Confirm(Are you sure);

11. msdocument.wrirte(The correct answer is “+z+”);

12. var x= parsefloatprompt(What number is less than 10? “,”)

JAVASCRIPT: CONDITIONAL STATEMENTS
• While writing a program, there may be a situation when
you need to adopt one path out of the given two paths.
So you need to make use of conditional statements that
allow your program to make correct decisions and
perform right actions. Reference: Tutorial Points.com

• Sometimes when you write code, you want to perform
different actions for different decisions. You can use
conditional statements in your code to do this.
Conditional statements are the set of commands used
to perform different actions based on different
conditions. JavaScript supports two conditional
statements: if...else and switch. Both perform in saw
way the same task. Reference:WebCheatSheet.com

JavaScript supports conditional statements
which are used to perform different actions
based on different conditions. Here we will
explain if..else statement.
JavaScript supports following forms
of if..else statement:
if statement
if...else statement
if...else if... statement.

if statement:
The if statement is the fundamental control statement
that allows JavaScript to make decisions and execute
statements conditionally.

Syntax:
if (expression)
Statement(s) to be executed if expression is true
}

Here JavaScript expression is evaluated. If the resulting value
is true, given statement(s) are executed.
If expression is false then no statement would be not executed.
Most of the times you will use comparison operators while
making decisions.

Example:
<html>
<body>
<script >
var x=prompt(“HTML stands for?”,””);
var y= “Hypertext Mark Up Language”
if(x==y)
alert(“Correct");
If(x!=y)
alert(“Wrong”);
</script>
</body>
</html>

if...else statement:
The if...else statement is the next form of control statement that
allows JavaScript to execute statements in more controlled way.
Syntax:
if (expression)
{
Statement(s) to be executed if expression is true
}
else
{
Statement(s) to be executed if expression is false
}

Here JavaScript expression is evaluated. If the resulting value
is true, given statement(s) in the if block, are executed.
If expression is false then given statement(s) in the else block, are
executed.

EXAMPLE
<html>
<body>
<script>
var x= parseFloat(prompt("Kilobytes is consist of how many bytes? ","
"));
var y= "1000"
if(x==y)
{
alert("Yes, Kilobytes is equal to "+x+" bytes");
}
else
{
alert("No, Kilobytes is not equal to "+x+" bytes");
}
</script>
</body>
</html>

if...else if... statement:
The if...else if... statement is the one level
advance form of control statement that
allows JavaScript to make correct decision
out of several conditions.

There is nothing special about this code. It is just a
series of if statements, where each if is part of
the else clause of the previous statement.
Statement(s) are executed based on the true
condition, if non of the condition is true
then else block is executed

Syntax:
if (expression 1)
{
Statement(s) to be executed if expression 1 is true
}
else if (expression 2)
{
}
else if (expression 3)
{
}
else
{
Statement(s) to be executed if no expression is true
}

EXERCISES/COMPUQUIZ
Write a JavaScript source code using if…else
conditional statements.
var year= Enter your birth year
Expression and statements

1970-1975 Your age is between 38-43 years old
1986-2013 Your age is between 0-27 year/s old

Javascript conditional statements 1

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