JS Loop

Loops can be execute a block of code a number of times.

Types of Loop

There are 4 types of loops in JavaScript that is.

for loop
while loop
do-while loop
for-in loop

1) For loop in JavaScript

In for loop is used to repeat the execution of the statements until a certain condition holds.

Syntax:

for (initialization condition; testing condition; increment/decrement)
{
    statement(s)
} 
            

Flow Chart :-

Example:-

<script>
for (i=1; i<=5; i++)
{
document.write(i + "<br/>")
}
</script>

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2) while loop in JavaScript

In while loop check the condition is true,the code inside the while loop is executed.when the condition is false the loop will be stops

Syntax:

while(condition){
statement executed...
}         

Example:- Print Fibonacci series

<html>
<head></head>
<body>  
	<script type="text/javascript">
		document.write("<b>Using while loops Example</b><br />");
		var i = 0, j = 1, k;
		document.write("Fibonacci series less than 40<br />");
		while(i<40)
		{
			document.write(i + "<br />");
			k = i+j;
			i = j;
			j = k;
		}
	</script>
</body>  
  </html>

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3) do-while loop JavaScript

In do while loop body of the loop is executed(Check) at first. Then the condition is evaluated. If the condition evaluates is true, the body of the loop inside the do statement is executed again.this process continues until the condition evaluates is to be false. Then the loop stops.

Syntax:

do {
    // body of loop
} while(condition)       

Example:- Print Even numbers

<html>
<head>
	<script type="text/javascript">
		document.write("<b>Using do...while loops </b><br />");
		var i = 2;
		document.write("Even numbers less than 20<br />");
		do
		{
			document.write(i + "<br />");
			 i = i + 2;
		}while(i<20)
	</script>
</head>
<body>
</body>
  </html>

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JS Tutorials

JS Loop

Types of Loop

1) For loop in JavaScript

2) while loop in JavaScript

3) do-while loop JavaScript