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Stingray is a small beacon library that can send small packets of information to your server. This can be really helpful to get some insight in how your front-end application is running and can provide additional information when "shit hits the fan".

The transport of this information is done using beacons. This will send an GET request to your server with a massive query string that will contain all the information.

By default we add the following information to the generated query string:

  • navigator (all strings, numbers, boolean values)
  • Properties from the document object:
    • document.charset as charset
    • document.domain as domain
    • document.inputEncoding as encoding
    • document.readyState as readyState
    • document.referrer as referrer
    • document.URL as url
    • document.visibilityState as visibility
  • performance.timing if exists
  • performance.memory if exists


Stingray was specifically written to be used in a system that supports commonjs, like browserify does and is therefor released in npm. Installation is as simple as typing the following command in your CLI:

npm install --save stingray


In all examples we assume that you've required the library as following:

'use strict';
var Stingray = require('stingray')
  , server = ''
  , stingray;

The Stingray constructor accepts 2 arguments:

  1. server, The address and or path that we need to send the gathered information to. This path/address needs to accept GET requests and parse our the supplied query string.
  2. options, Optional object which allows you to configure the Stingray instance. The following properties are accepted in the object:
    • limit: The maximum size of the URL that we can generate. Certain browsers like Internet Explorer have a maximum size and will error if URL's are generated that are larger. We default to lowest known limit of Internet Explorer when detected or default to 60.000 which seems to be the minimum in older Safari browsers.
    • document: Reference to the HTML document that we can use to create an element. This way we easily polyfill this for testing as well allow sending of data through an iframe element. Defaults to document global.
  • payload: Initial object which contains data that should be send to the server.
  • ignore: Object that instructs Stingray to ignore data structures it want to add by default. You can set the following properties: navigator, document, performance, timing and memory.
  • timeout: How long it can take for the beacon to load, if it takes longer we call the supplied callback with an error argument. Defaults to 1000 in the beacons module.

Now that we know the arguments it accepts we can construct our first Stingray instance.

stingray = new Stingray(server, { /* options, which are optional */ });


There's already a lot of default debug information available but you might want to set some addition information that specific to your application or you just want to override some default values. The Stingray.set method accepts 2 arguments:

  1. key: The name of key you want to store or override.
  2. value: Data that you want to store or override with. Please note that we only accept booleans, numbers and strings as accepted values. All other values will be ignored.

This method returns it self once it's executed so you can chain it if you wish.

stingray.set('foo', 'bar')
        .set('bar', 'foo');


Now that you can set new information to the beacon request it's also good to know that you can remove it as well. The remove method accepts the keys of values that you want to remove from the internal dataset. You can supply it with multiple arguments to remove multiple keys:

stingray.remove('foo', 'bar');

But you can also use space/comma separation in the first argument to instruct multiple key removal.

stingray.remove('foo, bar');

It also chains, so you can use that as an alternate api as well:



This is where all the magic actually happens. When you call the Stingray.write method it will send the beacon request to the server. It will return a boolean indicating if was successfully written. It can return false if the generated payload was to large and reached the limit of a single URL.

The write method accepts an option callback function which will be called once the payload has reached the server.

stingray.write(function () {
  // The only problem is that you don't know if beacon was processed succesfully
  // as there is no error support for failed beacons as it uses Image()'s
if (!stingray.write()) {
  console.log('payload to big', stingray.payload());


This method gathers all the information that should be transformed in to a query string and be send to the supplied server. So if you just want to have quick peek at the data, you can just call this method and it will return an object with all data.

// Example of the returned object
  "domain": "bar",
  "doNotTrack": "1",
  "onLine": true,
  "language": "en-US",
  "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.111 Safari/537.36",
  "product": "Gecko",
  "platform": "MacIntel",
  "appVersion": "5.0 (Macintosh; Intel Mac OS X 10_10_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.111 Safari/537.36",
  "appName": "Netscape",
  "appCodeName": "Mozilla",
  "hardwareConcurrency": 4,
  "vendor": "Google Inc.",
  "productSub": "20030107",
  "cookieEnabled": true,
  "charset": "UTF-8",
  "encoding": "UTF-8",
  "readyState": "complete",
  "url": "http://localhost:54181/__testling?show=true",
  "visibility": "visible",
  "loadEventEnd": 1415184360414,
  "loadEventStart": 1415184360414,
  "domComplete": 1415184360414,
  "domContentLoadedEventEnd": 1415184360384,
  "domContentLoadedEventStart": 1415184360384,
  "domInteractive": 1415184360384,
  "domLoading": 1415184360272,
  "responseEnd": 1415184360275,
  "responseStart": 1415184360268,
  "requestStart": 1415184360253,
  "connectEnd": 1415184360252,
  "connectStart": 1415184360252,
  "domainLookupEnd": 1415184360252,
  "domainLookupStart": 1415184360252,
  "fetchStart": 1415184360252,
  "navigationStart": 1415184360061,
  "jsHeapSizeLimit": 793000000,
  "usedJSHeapSize": 10000000,
  "totalJSHeapSize": 10000000



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