Examples

Take a look at the following example scripts showing how to use HAR API.

Do you have an issue with any of the following examples? Please file a report.

All examples bellow assume that the security token in your Firefox profile is set to test. This token needs to be set in extensions.netmonitor.har.contentAPIToken preference.

See more details about the extension setup.

Get HAR Data

This script shows how to trigger HAR export and get JSON data back (no local file created).

var options = {
  token: "test",    // Value of the token in your preferences
  getData: true,    // True if you want to get HAR data as a string
};

HAR.triggerExport(options).then(result => {
  console.log(result.data);
});

Get HARP Data

See how to get HARP file back from the collected data.

var options = {
  token: "test",
  getData: true,
  jsonp: true        // Get data as JSONP/HARP
};

HAR.triggerExport(options).then(result => {
  console.log(result.data);
});

Clear

It's possible to clear collected data at any time and export only new HTTP activity.

HAR.clear({token: "test"});

Save To File

This example shows how to trigger HAR export and save the log automatically in a local *.har file. The default target directory is <firefox-profile-dir>/har/logs. You can provide different directory path in devtools.netmonitor.har.defaultLogDir preference.

File name can use format string to have better control over the formatting of the generated file name.

var options = {
  token: "test",
  fileName: "my test har file %Y, %H:%M:%S"  // Name of the file
};

HAR.triggerExport(options).then(result => {
  // The local file is available now, result.data is null since options.getData wasn't set.
});

HAR API Ready

HAR API are injected into a browser tab asynchronously, so when the tab is opened it might take some time to have the API available. But, they are injected just once for the entire life time of the tab, no matter how many times is its content reloaded or navigated to different URL.

In any case, there is an event fired on the content window object when the API injection is done.

addEventListener("har-api-ready", event => {
  console.log("har api ready", event);
}, false);

Page Ready

Experimental feature (see also issue #10)

The extension is also firing new event on the content window object that can be used to detect that the page has been fully loaded. This event complements existing DOMContentLoaded and load events and is fired when the following conditions are true:

• Both DOMContentLoaded and load events has been fired
• There is no pending HTTP request
• No new HTTP request started in given period of time (1500ms by default, see also devtools.netmonitor.har.pageLoadedTimeout preference)

The same logic is used for auto-exporting HAR into a file when devtools.netmonitor.har.enableAutoExportToFile preference is set to true.

Example script:

addEventListener("har-page-ready", event => {
  var options = {
    token: "test",
    getData: true,
  };

  HAR.triggerExport(options).then(result => {
    console.log(result.data);
  });
});