The for...in loop is used to loop through
an object's properties. As we have not discussed Objects yet, you may not feel
comfortable with this loop. But once you understand how objects behave in
JavaScript, you will find this loop very useful.
Syntax
The syntax of ‘for..in’ loop is:
for (variablename
in object){
statement or block
to execute
}
In each iteration, one
property from object is assigned to variablename and this loop continues
till all the properties of the object are exhausted.
Example
Try the following
example to implement ‘for-in’ loop. It prints the web browser’s Navigator object.
<html>
<body>
<script
type="text/javascript">
<!--
var aProperty;
document.write("Navigator
Object Properties<br /> "); for (aProperty in navigator) {
document.write(aProperty);
document.write("<br
/>");
}
document.write
("Exiting from the loop!");
//-->
</script>
<p>Set the
variable to different object and then try...</p>
</body>
</html>
Output
Navigator Object
Properties
serviceWorker
webkitPersistentStorage
webkitTemporaryStorage
geolocation
doNotTrack
onLine
languages
language
userAgent
product
platform
appVersion
appName
appCodeName
hardwareConcurrency
maxTouchPoints
vendorSub
vendor
productSub
cookieEnabled
mimeTypes
plugins
javaEnabled
getStorageUpdates
getGamepads
webkitGetUserMedia
vibrate
getBattery
sendBeacon
registerProtocolHandler
unregisterProtocolHandler
Exiting from the
loop!
Set the variable
to different object and then try...
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