Javascript concept using history object

Question

I am interested in making a website that flashes through a visitors entire web history when they visit. I plan on using JavaScript to grab the history on each viewer's computer and animate through it with varying speeds depending on how much they had. My thought was to use history.length to determine the length of the visitor's history, and then use history.go() to navigate -1, -2, -3, etc. through the entire web history. I recognize that load times would be HUGE, but right now I am just trying to think through the concept. This related question seems like what I would use for the basis of my code, however, I don't understand why they describe that this method would not work. I am a student who is very new to JavaScript.

Do you guys have any knowledge of whether or not this will work, or any ideas on ways to achieve my idea?

Answer 1

You can call history.go() once. That's about as far as you'll get. The reason is simple, once you're on the previous page, your javascript is gone. Iframes won't work either due to the fact that you can't execute your own JS in an iframe that has a page from another domain. Read about same origin policy for more info on that.

The only real solution I can think of is a browser extension. The reason that'll work is due to the fact that your JS can persist across multiple sites. You'd probably just need a userscript in each page that does the following:

• check a variable to see if the functionality is enabled
• if it is, call history.go(-1) after a timeout (to control the speed)

I'm most familiar with Chrome so I'm imagining a browserAction to enable/disable the script and a content script that does the redirect. Other potential options include Greasemonkey (Firefox), Tampermonkey (Chrome), Personalized Web (Chrome) scripts

Answer 2

As stated in the question you linked to, JavaScript and / or the DOM does not give you access to the entire browser history since that would be a severe privacy violation. Imagine going to a site and having them be able to know every site you ever visited in that browser.

This would potentially give the site access to:

1. Sessions you are still logged into on other sites (if they store the session key in the URL, as some sites do)
2. Insight into what kind of activities you perform (are you a moderator on site X?)
3. Enormous amounts of data on what you are interested in.

This is not something that standards bodies or browser manufacturers thought users would be interested in sharing with everybody. That's why there isn't an API to walk through the browser's entire history.

@sachleen has already provided a very nice in-depth answer on how you can get around this limitation for individual browsers if you want to build this application. For the sake of completeness I'll simply mention the key term: "browser extension". :-)