You'd want to use a combination of WebStorage and Array. Basically, all the in-game stats can be easily kept track of via an array object, then when it comes time to save you can save it all as a string in WebStorage. Here's a really good tutorial on it.
That tutorial is as basic as you're going to get with what you're asking for, and it's the best tutorial for it, too.
One thing to keep in mind: it saves everything as a long string, so when it gets loaded back into the game data array all your integers become strings again, so any time you call a variable from the array and expect to use it as a number, remember to use the int(x) or float(x) System expressions to stay on the safe side.