JavaScript. Cycles

JavaScript supports different kinds of loops:

for - loops through a block of code a number of times;

for/in - loops through the properties of an object;

while - loops through a block of code while a specified condition is true;

do/while - also loops through a block of code while a specified condition is true.

For Loop: In the code below, for loop to go through all elements of array is implemented. We can use length property of JavaScript array to detect number of elements in array.

<script>

var person=new Array(); person[0]="sourav"; person[1]="Sathis";

person[2]="Nontey"; for(var i = 0;i< person.length;i++)

{ document.write("Person " + i + ": "+ person[i] + "<br>"); }

</script>

While Loop: In case of while loop there is only one condition within while() statement.

<script>

var person=new Array(); person[0]="sourav"; person[1]="Sathis";

person[2]="Nontey"; for(var i = 0;i< person.length;i++)

var i =0;

document.write("Using While loop" + "<br>");

while(i < person.length)

{document.write("Person " + i + ": "+ person[i] + "<br>");i++;} </script>

Do-While Loop: Do while is very similar with While loop but do- while is post checking loop. So, even if your condition is false loop will execute at least one time.

<script>

var person=new Array();

person[0]="sourav"; person[1]="Sathis"; person[2]="Nontey";

var i =0; document.write("Using Do-While loop" + "<br>");

do { document.write("Person " + i + ": "+ person[i] + "<br>");

i++; }while(i< person.length);

</script>