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When you need to make program to make decisions, conditional statements are used. In javascript we have following conditional statements:
- if statement - use this statement to execute some code only if a specified condition is true
- if...else statement - use this statement to execute some code if the condition is true and another code if the condition is false
- if...else if....else statement (nesting of if else)- use this statement to select one of many blocks of code to be executed
- switch statement - use this statement to select one of many blocks of code to be executed
If Statement:
Executes the code if a specific code is true
Syntax:
if(condition)
{
code
}
Example:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Siple Javascript conditions</title>
</head>
Syntax:
if(condition)
{
code
}
Example:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Siple Javascript conditions</title>
</head>
<body>
<button onclick="myFunction()">Try it</button>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction()
{
var x="";
var day=new Date().getDay();
if (day=="6")
{
x="Happy Weekend!";
}
document.getElementById("demo").innerHTML=x;
}
</script>
function myFunction()
{
var x="";
var day=new Date().getDay();
if (day=="6")
{
x="Happy Weekend!";
}
document.getElementById("demo").innerHTML=x;
}
</script>
</body>
</html>
</html>
If...else Statement
Use if..else statement to execute some code if a condition is true and another code if the condition is false
Syntax:
if (condition)
{
code
}
else
{
code
}
Example:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Siple Javascript conditions</title>
</head>
<body>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction()
{
var x="";
var day=new Date().getDay();
if (day=="6")
{
x="Happy Weekend!";
}
else{
x="Have a Good day";
}
document.getElementById("demo").innerHTML=x;
}
</script>
</body>
</html>
Syntax:
if (condition)
{
code
}
else
{
code
}
Example:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Siple Javascript conditions</title>
</head>
<body>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction()
{
var x="";
var day=new Date().getDay();
if (day=="6")
{
x="Happy Weekend!";
}
else{
x="Have a Good day";
}
document.getElementById("demo").innerHTML=x;
}
</script>
</body>
</html>
If...else if...else Statement
Use the if....else if...else statement to select one of several blocks of code to be executed.
Syntax:
if (condition1)
{
code
}
else if (condition2)
{
code
}
else
{
code
}
Example:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Siple Javascript conditions</title>
</head>
<body>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction()
{
var x="";
var day=new Date().getDay();
if (day=="6")
{
x="Happy Weekend!";
}
else if(day == "1"){
x="Have a Good start of a week";
}
else
{
x="Have a good day";
}
document.getElementById("demo").innerHTML=x;
}
</script>
</body>
</html>
Syntax:
if (condition1)
{
code
}
else if (condition2)
{
code
}
else
{
code
}
Example:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Siple Javascript conditions</title>
</head>
<body>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction()
{
var x="";
var day=new Date().getDay();
if (day=="6")
{
x="Happy Weekend!";
}
else if(day == "1"){
x="Have a Good start of a week";
}
else
{
x="Have a good day";
}
document.getElementById("demo").innerHTML=x;
}
</script>
</body>
</html>
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