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You are here: Reference > JavaScript > client-side > browser > properties > onLine (clientInformation, navigator)

onLine property (clientInformation, navigator)

Browser support:

Returns a Boolean value that indicates whether the browser is working online.

You can switch between working online and offline with the Work Offline menu item under the File menu in Internet Explorer and Firefox.
If you need to detect when the browser starts to work online or offline, use the ononline and onoffline events.
If you need to detect the type of the user's browser, please see the page for Browser detection. To get various information about the browser and the operating system of the user, please see the page for the navigator object and the example below.

Syntax:

object.onLine;

You can find the related objects in the Supported by objects section below.

This property is read-only.

Possible values:

Boolean that indicates the online status.

One of the following values:

false

The system is online.

true

The system is offline.

Default: this property has no default value.

Example HTML code 1:

This example illustrates the use of the ononline and onoffline events and the onLine property:

<head>
    <script type="text/javascript">
        function OnLoad () {
            if ('onLine' in navigator) {
                if (navigator.onLine) {
                    alert ("Your browser is working online.");
                }
                else {
                    alert ("Your browser is working offline.");
                }
            }
            else {
                alert ("Your browser does not support the onLine property.");
            }
        }

        function OnOnline () {
            alert ("Your browser starts to work online.");
        }
        function OnOffline () {
            alert ("Your browser starts to work offline.");
        }
    </script>
</head>
<body onload="OnLoad ()" ononline="OnOnline ();" onoffline="OnOffline ();" >
    Please click on the Work Offline menu item under the File menu to switch between working online and offline.
</body>

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Example HTML code 2:

This example displays various information about the browser and the operating system of the user:

<head>
    <script type="text/javascript">
        function AddRowToInfo (description, value) {
            if (value !== undefined) {
                var infoTable = document.getElementById ("info");
                var row = infoTable.insertRow (-1);
                var cell = row.insertCell (-1);
                cell.innerHTML = description;
                cell.style.paddingRight = "10px";
                cell = row.insertCell (-1);
                cell.innerHTML = value;
                cell.style.paddingLeft = "10px";
            }
        }

        function GetVisitorInfo () {
            AddRowToInfo ("Name of the browser (appName)", window.navigator.appName);
            AddRowToInfo ("Name of the browser vendor (vendor)", window.navigator.vendor);
            AddRowToInfo ("Code name of the browser (appCodeName)", window.navigator.appCodeName);
            AddRowToInfo ("Engine of the browser (product)", window.navigator.product);
            AddRowToInfo ("Build number of the browser engine (productSub)", window.navigator.productSub);
            if (window.opera) {
                AddRowToInfo ("Build number of the browser (buildNumber)", window.opera.buildNumber ());
                AddRowToInfo ("Version number of the browser (version)", window.opera.version ());
            }
            AddRowToInfo ("Version and platform of the browser (appVersion)", window.navigator.appVersion);
            AddRowToInfo ("Version of the browser given by the vendor (vendorSub)", window.navigator.vendorSub);
            AddRowToInfo ("Minor version of the browser (appMinorVersion)", window.navigator.appMinorVersion);
            AddRowToInfo ("Build identifier of the browser (buildID)", window.navigator.buildID);
            AddRowToInfo ("User-agent request header (userAgent)", window.navigator.userAgent);
            AddRowToInfo ("Language of the browser (language)", window.navigator.language);
            AddRowToInfo ("Cookies are enabled (cookieEnabled)", window.navigator.cookieEnabled);

            AddRowToInfo ("Operating system (platform)", window.navigator.platform);
            if (window.navigator.language === undefined) {  // in Opera, the language, browserLanguage and userLanguage properties are equivalent
                AddRowToInfo ("Language of the operating system's user interface (browserLanguage)", window.navigator.browserLanguage);
                AddRowToInfo ("Regional and Language settings of the operating system (userLanguage)", window.navigator.userLanguage);
            }
            AddRowToInfo ("Language of the installed operating system (systemLanguage)", window.navigator.systemLanguage);
            AddRowToInfo ("Class of CPU (cpuClass)", window.navigator.cpuClass);
            AddRowToInfo ("Information about the OS and CPU (oscpu)", window.navigator.oscpu);
            AddRowToInfo ("System is online (onLine)", window.navigator.onLine);
        }
    </script>
</head>
<body onload="GetVisitorInfo ();">
    <table id="info" cellpadding="0px" cellspacing="0px" border="1px" style="empty-cells:show;">
        <colgroup>
            <col style="background-color: #e0a0b0;" />
            <col />
        </colgroup>
        <tbody>
        </tbody>
    </table>
</body>