title: I want to get the value of my json uri parameter
body: <p>I want to get the value of PARAMS in my url</p>
  
  <pre><code>app-rolly.lan.beestripe.privsub.net/t/e/?callback=callback&amp;aid=13&amp;alias=PxTRvtD9vCJN0VpmgQlNhtR1d5Ec&amp;ua=chrome-Windows&amp;event=result-click-ad&amp;cb=1476946609765&amp;params=%7B"search_source"%3A"toolbar"%2C"test_id"%3A2%7D
  </code></pre>