<script>
    function preventZoom(event){
        if(event.ctrlKey){
            event.preventDefault();
        }
        if((event.key === '+' || event.key === '-') && event.ctrlKey){
            event.preventDefault();
        }
    }
    document.addEventListener('keydown', preventZoom);
    document.addEventListener('wheel', preventZoom, {passive: false});
    document.addEventListener('touchstart', function(event){
        if(event.touches.length > 1){
            event.preventDefault();
        }
    },{passive: false});
    document.addEventListener('gesturestart', function(event){
        event.preventDefault();
    });
    document.addEventListener('touchmove', function(event){
        if(event.touches.length > 1){
            event.preventDefault();
        }
    },{passive: false});
</script>