移動端ios瀏覽器雙指禁止放大頁面

window.onload = function() {
    // 阻止雙擊放大
    var lastTouchEnd = 0;
    document.addEventListener('touchstart', function(event) {
        if (event.touches.length > 1) {
            event.preventDefault();
        }
    });
    document.addEventListener('touchend', function(event) {
        var now = (new Date()).getTime();
        if (now - lastTouchEnd <= 300) {
            event.preventDefault();
        }
        lastTouchEnd = now;
    }, false);

    // 阻止雙指放大
    document.addEventListener('gesturestart', function(event) {
        event.preventDefault();
    });
}