How can I show all the localStorage saved variables?

You could try iterating through all of the items in the localStorage object:

for (var i = 0; i < localStorage.length; i++){
    // do something with localStorage.getItem(localStorage.key(i));
}

Console log the localStorage. It's very simple.

console.log(localStorage);

I use this block of code frequently:

var i;

console.log("local storage");
for (i = 0; i < localStorage.length; i++)   {
    console.log(localStorage.key(i) + "=[" + localStorage.getItem(localStorage.key(i)) + "]");
}

console.log("session storage");
for (i = 0; i < sessionStorage.length; i++) {
    console.log(sessionStorage.key(i) + "=[" + sessionStorage.getItem(sessionStorage.key(i)) + "]");
}