问题
How i can fetch the value of this input element in my main.js:
<input type="hidden" value="12124054" id="ctl00_cphContent_hdnID" name="ctl00$cphContent$hdnID">
I tried var id = document.getElementById("ctl00_cphContent_hdnPlayerID").value; and contentWindow.document.getElementById("ctl00_cphContent_hdnPlayerID").focus(); but i am getting errors that document and contentWindows are unidentified :(
回答1:
You need to get the value from the page using a content script and then send the value to main.js - this is because web content is inherently untrusted by the addon-sdk. Please see these docs for more on how to use content scripts:
https://addons.mozilla.org/en-US/developers/docs/sdk/1.0/dev-guide/addon-development/web-content.html#content_script_events
Here is an example add-on on Builder that shows how to pass values frmo the content script back to main.js. In this case I'm using the xui library to more easily bind events in the pgae.
来源：https://stackoverflow.com/questions/12826256/get-value-of-an-input-element-on-a-firefox-addon