A defer script execution snippet for only executing a callback on user interaction

deferScriptExecution.js

function deferStartTillUserAction(cb) {
    var locked = true;
    var didClick = false;
    var didScroll = false;

    function unlock() {
        if (locked) {
            locked = false;
            cb();
        }
    }

    function deferMove(_ref) {
        unlock();
    }

    function deferTouch(event) {
        if (locked) {
            deferMove(event);
            var target = event.target; // on iOS links can be not clicked through images
            if (!didClick && !didScroll) {
                target.click();
            }
        }
    }

    function deferScroll(event) {
        didScroll = true;
        deferMove(event);
    }

    function deferClick(event) {
        didClick = true;

        if (locked) {
            unlock();
        }
    }

    document.addEventListener("click", deferClick, true);
    document.addEventListener("mousemove", deferMove, true);
    document.addEventListener("keydown", deferMove, true);
    document.addEventListener("touchstart", deferTouch, true);
    window.addEventListener("scroll", deferScroll); // TODO: start js if some placeholder (pagination?, lazy image?) is visible
}

deferStartTillUserAction(function () {
    //whatever callback you want to execute
})