webApp禁止页面整体下拉，不影响页面内部scroll

转载webApp禁止页面整体下拉，不影响页面内部scroll

var overscroll = function(el) {
    el.addEventListener('touchstart', function() {
         var top = el.scrollTop,
             totalScroll = el.scrollHeight,
             currentScroll = top + el.offsetHeight
             //If we're at the top or the bottom of the containers
             //scroll, push up or down one pixel.
             //
             //this prevents the scroll from "passing through" to
             //the body.
         if(top === 0) {
             el.scrollTop = 1
         } else if(currentScroll === totalScroll) {
             el.scrollTop = top - 1
         }
     })
     el.addEventListener('touchmove', function(evt) {
         //if the content is actually scrollable, i.e. the content is long enough
         //that scrolling can occur
         if(el.offsetHeight < el.scrollHeight)
             evt._isScroller = true
     })
 }
 overscroll(document.querySelector('.scroll'));//允许滚动的区域
 document.body.addEventListener('touchmove', function(evt) {
     //In this case, the default behavior is scrolling the body, which
     //would result in an overflow.  Since we don't want that, we preventDefault.
     if(!evt._isScroller) {
         evt.preventDefault()
     }
 })