Javascript Course


The break and continue can be used in JavaScript with loop instrucxtions: for() and while() to stop or "jump over" loops.


The break statement

The break statement stops the execution of a repetitive instruction.
- Example, a for() loop is stoped with 'break':
<script>
//defined to run till x is 10
for(x=0; x<10; x++){
 document.write('<br> X is '+x);

 //stops completely the loop when x is 3
 if(x==3) break;
} 
</script>
In the same way you can use it with while():
<script>
var x =0;

//defined to run till x is 10
while(x <10){
 document.write('<br> X este '+x);

 //stops completely the loop when x is 3
 if(x==3) break;
 x++;
} 
</script>

The continue statement

The continue statement breaks one iteration (in the loop), if a specified condition occurs, and continues with the next iteration in the loop..
- This example skips the value of 1 and 3:
<script>
//defined to run from 0 to 5
for(x=0; x<5; x++){
 //skips the execution when x is 1 or 3
 if(x ==1 || x ==3) continue;
 document.write('<br> X ise '+x);
} 
</script>
In the same way you can use it with while():
<script>
var x =0;

//defined to run from 0 to 5
while(x <5){
 //skips the execution when x is 1 or 3
 if(x ==1 || x ==3){
 x++; //to increment when it jumps over iteration
 continue;
 }

 document.write('<br> X este '+x);
 x++;
} 
</script>

JS label statements

label statements can be used in JavaScript with 'break' or 'continue'. It labels a group of nested repetitive instructions, allowing control over that group inside the nested instructions.

Syntax:
label_name:
for(...){
 //other instructions with for() or while()
}
- 'label_name' can be any name (except the reserved JavaScript keywords), followed by : and the nested group of for() or while().

Studying the following example, you can better understand how the 'label' it works:
<script>
loopX: //labels the next set of nested instructions
for(var x=0; x<5; x++){
 document.write('<h4>X - '+x+'</h4>');
 for(var y=0; y<3; y++){
 //stops execution of the entire group when x is 2
 if(x ==2) break loopX;

 document.write('<br>Y = '+y);
 }
}
</script>

- Testing the code, you will see that though 'break' is inside the second 'for()', by specifying 'loopX', which is the label of the entire set of nested instructions, it will stops the execution of entire group.

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
Which type of <input> creates a date input control, such as a pop-up calendar?
type="text" type="date" type="button"
<input type="date" name="set_date" value="2012-10-15" />
Which CSS property adds shadow effects to the text of an element?
font-style color text-shadow
h2 {
  text-shadow: 2px 3px 3px #a0a1fe;
}
Click on the function that adds new elements to the end of an array.
pop() shift() push()
var pags = ["lessons", "courses"];
pags.push("download", "tutorials");
alert(pags[2]);            // download
Which function sorts an array by key, in ascending order, maintaining key to data correlations?
asort() ksort() sort()
$lang =[10=>"PHP", 20=>"JavaScript", "site"=>"coursesweb.net");
ksort($lang);
var_export($lang);     // array ("site"=>"coursesweb.net", 10=>"PHP", 20=>"JavaScript")
break, continue, and label

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