Javascript – while
Loops can execute a block of code a number of times.
The code:
<!DOCTYPE html>
<html>
<body>
<p>Click the button to loop through a block of as long as <em>i</em> is less than 5.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction()
{
var x="",i=0;
while (i<5) // If you forget to increase the variable used your browser will crash.
{
x=x + "The number is " + i + "<br>";
i++;
}
document.getElementById("demo").innerHTML=x;
}
</script>
</body>
</html>
The function execute:
document.getElementById("demo").innerHTML=x;
for 5 times, the result is:
The number is 0
The number is 1
The number is 2
The number is 3
The number is 4
Syntax:
1) It checks the condition
2) It executes the code
while (condition)
{
... you want to do ...
}
Syntax:
1) It executes the code -> The loop will always be executed at least once, even if the condition is false.
2) It checks the condition
... you want to do ...
{
... you want to do ...
}
while (condition)
To read an Array:
<!DOCTYPE html>
<html>
<body>
<script>
cars=["BMW","Volvo","Saab","Ford"];
var i=0;
while (cars[i])
{
document.write(cars[i] + "<br>");
i++;
}
</script>
</body>
</html>
