The Navigator.productSub read-only property returns the build number of the current browser.


prodSub = window.navigator.productSub
  • prodSub is a string.


function prodsub() {
  var dt = document.getElementById("d").childNodes[0]; = window.navigator.productSub;

<button onclick="prodsub();">productSub</button>
// returns: 20010725


On IE, this property returns undefined.

On Apple Safari and Google Chrome this property always returns 20030107.


Specification Status Comment
HTML Living Standard
The definition of 'NavigatorID: productSub' in that specification.
Living Standard Initial definition

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support Yes1 ? Yes Yes2 ? Yes1
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support ? Yes1 ? Yes ? Yes1 ?

1. Always returns 20030107.

2. Always returns undefined.

Document Tags and Contributors

Last updated by: mfuji09,