DAY - 8
JavaScript - Loop Control
Ø JavaScript provides full control to handle loops and
switch statements. There may be a situation when you need to come out of a loop
without reaching its bottom. There may also be a situation when you want to
skip a part of your code block and start the next iteration of the loop.
Ø To handle all such situations, JavaScript
provides break and continuestatements. These statements
are used to immediately come out of any loop or to start the next iteration of
any loop respectively.
The break Statement
Ø The break statement,
which was briefly introduced with the switch statement,
is used to exit a loop early, breaking out of the enclosing curly braces.
Ø Flow Chart
Ø The following example illustrates the use of a break statement with a while loop.
Notice how the loop breaks out early once x reaches 5 and reaches to document.write (..) statement just below to the closing curly
brace −
<html>
<body>
<scripttype="text/javascript">
<!--
var x =1;
document.write("Entering the loop<br
/> ");
while(x <20)
{
if(x ==5){
break; // breaks out of loop completely
}
x = x +1;
document.write( x+"<br />");
}
document.write("Exiting the loop!<br
/> ");
//-->
</script>
<p>Set the variable to
different value and then try...</p>
</body>
</html>
Output
Entering the loop
2
3
4
5
Exiting the loop!
The continue Statement
Ø The continue statement
tells the interpreter to immediately start the next iteration of the loop and
skip the remaining code block.
Ø When a continuestatement
is encountered, the program flow moves to the loop check expression immediately
and if the condition remains true, then it starts the next iteration, otherwise
the control comes out of the loop.
Ø This example illustrates the use of a continue statement with a while
loop. Notice how the continue statement
is used to skip printing when the index held in variable x reaches 5 −
<html>
<body>
<script type="text/javascript">
<!--
var x =1;
document.write("Entering the loop<br
/> ");
while(x <10)
{
x = x +1;
if(x ==5){
continue; // skip rest of the loop body
}
document.write( x+"<br />");
}
document.write("Exiting the loop!<br
/> ");
//-->
</script>
<p>Set the variable to
different value and then try...</p>
</body>
</html>
Output
2
3
4
6
7
8
9
10
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