basically, I am trying to scrape webpages with php but I want to do so after the initial javascript on a page executes - I want access to the DOM after initial ajax requests, etc... is there any way to do this?
Short answer: no.
Scraping a site gives you whatever the server responds with to the HTTP request that you make (from which the "initial" state of the DOM tree is derived, if that content is HTML). It cannot take into account the "current" state of the DOM after it has been modified by Javascript.
I'm revising this answer because there are now several projects that do a really good job of this:
PhantomJS is a headless version of WebKit, and there are some helpful wrappers such as CasperJS.
Zombie.js which is a wrapper over jsdom written in Javascript (Node.js).
You need to write JavaScript code to interact with both of these projects. I like Zombie.js better so far, since it is easier to set up, and you can use any Node.js/npm modules in your code.
Old answer:
No, there's no way to do that. You'd have to emulate a full browser environment inside PHP. I don't know of anyone who is doing this kind of scraping except Google, and it's far from comprehensive.
Instead, you should use Firebug or another web debugging tool to find the request (or sequence of requests) that generates the data you're actually interested in. Then, use PHP to perform only the needed request(s).
来源：https://stackoverflow.com/questions/11214122/php-file-get-contents-after-javascript-executes