If Statement
- In JavaScript, an if statement allows you to execute a block of code if a specified condition is true, and optionally execute a different block of code if the condition is false.
There are three types of if statements:
- if statement
- if else statement
- if else if statement
if statement:
- if an expression is true it evaluates content only.
Syntax:
if (condition) {
// Code to be executed if the condition is true
}
Flow chart:
Example:
<html>
<body>
<script>
var a = 20;
if (a % 2 == 0) {
document.write("a is even number");
}
else {
document.write("a is odd number");
}
</script>
</body>
</html>
Output:
a is an even number
If else statement:
- If the condition is true then the if block will execute and if false then the else block will execute
Syntax:
if(expression){
// if condition is true
}
else{
//content to be evaluated if condition is false
}
Flow chart:
Example:
<html>
<body>
<script>
var a = 20;
if (a % 2 == 0) {
document.write("a is even number");
}
else {
document.write("a is odd number");
}
</script>
</body>
</html>
if else if statement:
- if else if evaluates the content if the expression is true from several expressions.
Syntax:
if(expression1){
//content to be evaluated if expression1 is true
}
else if(expression2){
//content to be evaluated if expression2 is true
}
else if(expression3){
//content to be evaluated if expression3 is true
}
else{
//content to be evaluated if no expression is true
}
Example:
<html>
<body>
<script>
var a=20;
if(a==10){
document.write("a is equal to 10");
}
else if(a==15){
document.write("a is equal to 15");
}
else if(a==20){
document.write("a is equal to 20");
}
else{
document.write("a is not equal to 10, 15 or 20");
}
</script>
</body>
</html>
Output:
a is equal to 20