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    This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

    The Navigator.mozIsLocallyAvailable() method allows add-ons to determine whether or not a given resource is available.

    Note: Security exceptions can occur if the requested URI is not from the same origin.


    navigator.mozIsLocallyAvailable(uri, ifOffline);


    The URI of the resource whose availability is to be checked, as a string.

    Allows you to specify whether or not the offline resources cache should be checked; specify true to consider the offline resources cache.


    var available = navigator.mozIsLocallyAvailable("my-image-file.png", true);
    if (available) {
      /* the offline resource is present */
    } else {
      console.log("Certain needed resources are not available offline");


    Not part of any specifications.

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support Not supported (Yes)
    Removed in 35 (35)
    Not supported Not supported Not supported
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support Not supported Not supported (Yes)
    Removed in 35.0 (35)
    Not supported Not supported Not supported

    Document Tags and Contributors

    Contributors to this page: Sheppy, fscholz, Waldo, teoli, ziyunfei, Mgjbot, kscarfone, iamanupmenon, MHasan
    Last updated by: fscholz,
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