如题：

document.getElementById('recPages').addEventListener('touchstart', touch, true);
document.getElementById('recPages').addEventListener('touchmove', touch, true);
document.getElementById('recPages').addEventListener('touchend', touch, true);
function touch(event) {
        var event = event || window.event;
        var targetTagName = event.target.tagName.toLowerCase();
        var targetTr = event.target.parentNode.parentNode;
        var id = targetTr.id;
        if (targetTr.id.indexOf('_') > -1) {
            id = targetTr.id.substr(targetTr.id.indexOf('_') + 1, targetTr.id.length);
        }
        switch (event.type) {
            case "touchstart":
                alert('start');
                break;
            case "touchend":
                alert('end')
                break;
            case "touchmove":
            alert('move')
                break;
        }

    }

代码如上，这样写，是哪里出问题了吗？