fnMove(e, posX, posY) posX, posY代表什么

Question

function getByClass(clsName, parent) {    var oParent = parent ? document.getElementById(parent) : document,        eles = [],        elements = oParent.getElementsByTagName('*');    for (var i = 0, l = elements.length; i < l; i++) {        if (elements[i].className == clsName) {            eles.push(elements[i]);        }    }    return eles;}window.onload = drag;function drag() {    var oTitle = getByClass('login_logo_webqq', 'loginPanel')[0];    // 拖曳    oTitle.onmousedown = fnDown;    // 关闭    var oClose = document.getElementById('ui_boxyClose');    oClose.onclick = function () {            document.getElementById('loginPanel').style.display = 'none';        }        // 切换状态    var loginState = document.getElementById('loginState'),        stateList = document.getElementById('loginStatePanel'),        lis = stateList.getElementsByTagName('li'),        stateTxt = document.getElementById('login2qq_state_txt'),        loginStateShow = document.getElementById('loginStateShow');    loginState.onclick = function (e) {        e = e || window.event;        if (e.stopPropagation) {            e.stopPropagation();        } else {            e.cancelBubble = true;        }        stateList.style.display = 'block';    }    // 鼠标滑过、离开和点击状态列表时    for (var i = 0, l = lis.length; i < l; i++) {        lis[i].onmouseover = function () {            this.style.background = '#567';        }        lis[i].onmouseout = function () {            this.style.background = '#FFF';        }        lis[i].onclick = function (e) {            e = e || window.event;            if (e.stopPropagation) {                e.stopPropagation();            } else {                e.cancelBubble = true;            }            var id = this.id;            stateList.style.display = 'none';            stateTxt.innerHTML = getByClass('stateSelect_text', id)[0].innerHTML;            loginStateShow.className = '';            loginStateShow.className = 'login-state-show ' + id;        }    }    document.onclick = function () {        stateList.style.display = 'none';    }}function fnDown(event) {    event = event || window.event;    var oDrag = document.getElementById('loginPanel'),        // 光标按下时光标和面板之间的距离        disX = event.clientX - oDrag.offsetLeft,        disY = event.clientY - oDrag.offsetTop;    // 移动    document.onmousemove = function (event) {            event = event || window.event;            fnMove(event, disX, disY);        }        // 释放鼠标    document.onmouseup = function () {        document.onmousemove = null;        document.onmouseup = null;    }}function fnMove(e, posX, posY) {    var oDrag = document.getElementById('loginPanel'),        l = e.clientX - posX,        t = e.clientY - posY,        winW = document.documentElement.clientWidth || document.body.clientWidth,        winH = document.documentElement.clientHeight || document.body.clientHeight,        maxW = winW - oDrag.offsetWidth - 10,        maxH = winH - oDrag.offsetHeight;    if (l < 0) {        l = 0;    } else if (l > maxW) {        l = maxW;    }    if (t < 0) {        t = 10;    } else if (t > maxH) {        t = maxH;    }    oDrag.style.left = l + 'px';    oDrag.style.top = t + 'px';}

Answer 1

 disX = event.clientX - oDrag.offsetLeft,

        disY = event.clientY - oDrag.offsetTop;

    // 移动

    document.onmousemove = function (event) {

            event = event || window.event;

            fnMove(event, disX, disY);

代码里 fnDown函数里调用了fnMove函数（    fnMove(event, disX, disY);），里面就传递了3个参数：event, disX, disY，相对应的e, posX, posY。

fnDown中有给disX, disY赋值（光标按下时光标和面板之间的距离）。

 disX = event.clientX - oDrag.offsetLeft,

  disY = event.clientY - oDrag.offsetTop;