IOS 禁止页面双击放大，双指缩放功能

代码如下，忘了是哪位大哥的博客里的

window.onload=function () {
                document.addEventListener('touchstart',function (event) {
                    if(event.touches.length>1){
                        event.preventDefault();
                    }
                });

                var lastTouchEnd=0;

                document.addEventListener('touchend',function (event) {
                    var now=(new Date()).getTime();
                    if(now-lastTouchEnd<=300){
                        event.preventDefault();
                    }
                    lastTouchEnd=now;

                },false);

                document.addEventListener('gesturestart', function (event) {
                    event.preventDefault();
                });
            }