H5 web page disables double-click/two-finger zoom

```html ``` ```javascript 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(); }); } ```