兼容问题

HTML：

ios Safari浏览器无法禁止用户缩放

    window.onload = function() {
        const lastTouchEnd = 0;
        document.addEventListener('touchstart', function(event) {
            if (event.touches.length > 1) {
                event.preventDefault();
            }
        });
        document.addEventListener('touchend', function(event) {
            const now = (new Date()).getTime();
            if (now - lastTouchEnd <= 300) {
                event.preventDefault();
            }
            lastTouchEnd = now;
        }, false);
        document.addEventListener('gesturestart', function(event) {
            event.preventDefault();
        });
        document.addEventListener('dblclick', function (event) {
            event.preventDefault();
        })
    };