javascript - How to get another web page data within background script of Chrome extension?

Question

I'm trying to read some data from HTML web page from specified web site, in my Chrome extension. I tried many scripts but not succeed, and now trying with following..

chrome.webRequest.onBeforeRequest.addListener(
        function(details)
        {
          alert('ok');
          alert( details.requestBody);
        },
        {
          urls: ["https://www.thefreedictionary.com/test"]
        },
        ['requestBody']
     );

The scripts runs without error, but callback never fires. I tried with different url's, but none of them worked. The alert never shown.

Can anyone find what I'm doing wrong here?

I just want to read web page from background script. I'm interested to use solution including something like below to define UserAgent.

    myHttpWebRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)";//"Mozilla/5.0 (Windows NT 6.1; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0";

Any help would be highly appreciated.

Answer 1

等待大神答复