H5网页禁用双击/双指放大

<meta name="viewport" content="width=device-width,initial-scale=1.0,minimum-scale=1.0,maximum-scale=1.0,user-scalable=0">

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();
  });
}