chrome/common/extensions/docs/templates/intros/devtools_network.html

<p>
See <a href="devtools">DevTools APIs summary</a> for
general introduction to using Developer Tools APIs</a>.
</p>

<h2 id="overview">Overview</h2>

<p>
Network requests information is represented in the HTTP Archive format
(<em>HAR</em>). The description of HAR is outside of scope of this document,
please refer to <a href=
"http://www.softwareishard.com/blog/har-12-spec/">
HAR v1.2 Specification</a>.
</p><p>
In terms of HAR, the
<code>chrome.devtools.network.getHAR()</code> method returns
entire <em>HAR log</em>, while
<code>chrome.devtools.network.onRequestFinished</code> event
provides <em>HAR entry</em> as an argument to the event callback.
</p>
<p>Note that request content is not provided as part of HAR for efficieny
reasons. You may call request's <code>getContent()</code> method to retrieve
content.
<p>If the Developer Tools window is opened after the page is loaded,
some requests may be missing
in the array of entries returned by <code>getHAR()</code>.
Reload the page to get all requests.
In general, the list of
requests returned by <code>getHAR()</code> should match that displayed in
the Network panel.
<h2 id="overview-examples">Examples</h2>

<p>The following code logs URLs of all images larger than 40KB as they are
loaded:</p>

<pre>
chrome.devtools.network.onRequestFinished.addListener(
    function(request) {
      if (request.response.bodySize > 40*1024)
      chrome.experimental.devtools.console.addMessage(
          chrome.experimental.devtools.console.Severity.Warning,
          "Large image: " + request.request.url);
});
</pre>

<p>
You can find more examples that use this API in
<a href="samples#devtools.network">Samples</a>.
</p>