jQuery.touchScrollBuster.js

/*!
    jQuery.touchScrollBuster v0.0.1
    Tay Yang Shun https://github.com/yangshun

    The MIT License (MIT)
    Copyright (c) 2015
    
    $(el).touchScrollBuster() will prevent parent containers from scrolling
    when the child container is at the top or at the bottom.
*/

(function($) {

    var lockTop = false;
    var lockBottom = false;
    var lastY = 0;

    $.fn.touchScrollBuster = function () {
        $(this).on('touchstart' , function (e) {
            var target = e.currentTarget;
            var currentScrollPos = $(target).scrollTop();
            lockTop = false;
            lockBottom = false;
            if (currentScrollPos === 0) { 
                lockTop = true;
                lastY = e.originalEvent.touches[0].clientY;
            } else if (currentScrollPos === target.scrollHeight - target.offsetHeight) { 
                lockBottom = true;
                lastY = e.originalEvent.touches[0].clientY;
            }
        });

        $(this).on('touchmove' , function (e) {
            var currentY = e.originalEvent.touches[0].clientY;
            if ((lockTop && (currentY > lastY)) || 
                (lockBottom && (currentY < lastY))) {
                e.preventDefault();
            }
        });
    }

}(window.jQuery || window.Zepto));