There are many properties in an object. When you have to loop through a particular object’s properties, then for…in the loop is used.
Following is the syntax used for for…in loop in JavaScript code:
for (variablename in object) {
The Statement(s) or the block that has to be executed
}When the iteration of the properties' properties takes place, each property is provided with a unique variable name, and the exhaustion of the respective process (or a loop) takes place when each property of the object is provided with a unique variable name.
Following is an example of a JavaScript code using above mentioned for…in the loop:
<html>
<body>
<script type = "text/javascript">
<!--
var aProperty;
document.write("RegExp <br /> ");
for (aProperty in RegExp) {
document.write(aProperty);
document.write("<br />");
}
document.write ("Loop Ended");
//-->
</script>
</body>
</html>The output for the program is:
RegExp
input
multiline
lastMatch
lastParen
leftContext
rightContext
$1
$2
$3
$4
$5
$6
$7
$8
$9
Loop Ended
