javaScript中返回true和false的问题,求大神解答!!
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  User: TopbeCoder5
  Date: 2015/1/18
  Time: 20:44
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--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>测试alertMsg</title>
    <link href="css/alertMsg.css" rel="stylesheet" type="text/css"/>
    <script type="text/javascript">
        function alertMsg(msg, mode) { //mode为空,即只有一个确认按钮,mode为1时有确认和取消两个按钮
            msg = msg || '';
            mode = mode || 0;
            var top = document.body.scrollTop || document.documentElement.scrollTop;
            var isIe = (document.all) ? true : false;
            var isIE6 = isIe && !window.XMLHttpRequest;
            var sTop = document.documentElement.scrollTop || document.body.scrollTop;
            var sLeft = document.documentElement.scrollLeft || document.body.scrollLeft;
            var winSize = function () {
                var xScroll, yScroll, windowWidth, windowHeight, pageWidth, pageHeight;
                // innerHeight获取的是可视窗口的高度,IE不支持此属性
                if (window.innerHeight && window.scrollMaxY) {
                    xScroll = document.body.scrollWidth;
                    yScroll = window.innerHeight + window.scrollMaxY;
                } else if (document.body.scrollHeight > document.body.offsetHeight) { // all but Explorer Mac
                    xScroll = document.body.scrollWidth;
                    yScroll = document.body.scrollHeight;
                } else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
                    xScroll = document.body.offsetWidth;
                    yScroll = document.body.offsetHeight;
                }

                if (self.innerHeight) {    // all except Explorer
                    windowWidth = self.innerWidth;
                    windowHeight = self.innerHeight;
                } else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
                    windowWidth = document.documentElement.clientWidth;
                    windowHeight = document.documentElement.clientHeight;
                } else if (document.body) { // other Explorers
                    windowWidth = document.body.clientWidth;
                    windowHeight = document.body.clientHeight;
                }

                // for small pages with total height less then height of the viewport
                if (yScroll < windowHeight) {
                    pageHeight = windowHeight;
                } else {
                    pageHeight = yScroll;
                }

                // for small pages with total width less then width of the viewport
                if (xScroll < windowWidth) {
                    pageWidth = windowWidth;
                } else {
                    pageWidth = xScroll;
                }

                return {
                    'pageWidth': pageWidth,
                    'pageHeight': pageHeight,
                    'windowWidth': windowWidth,
                    'windowHeight': windowHeight
                }
            }();
            //alert(winSize.pageWidth);
            //遮罩层
            var styleStr = 'top:0;left:0;position:absolute;z-index:10000;background:#666;width:' + winSize.pageWidth + 'px;height:' + (winSize.pageHeight + 30) + 'px;';
            styleStr += (isIe) ? "filter:alpha(opacity=80);" : "opacity:0.8;"; //遮罩层DIV
            var shadowDiv = document.createElement('div'); //添加阴影DIV
            shadowDiv.style.cssText = styleStr; //添加样式
            shadowDiv.id = "shadowDiv";
            //如果是IE6则创建IFRAME遮罩SELECT
            if (isIE6) {
                var maskIframe = document.createElement('iframe');
                maskIframe.style.cssText = 'width:' + winSize.pageWidth + 'px;height:' + (winSize.pageHeight + 30) + 'px;position:absolute;visibility:inherit;z-index:-1;filter:alpha(opacity=0);';
                maskIframe.frameborder = 0;
                maskIframe.src = "about:blank";
                shadowDiv.appendChild(maskIframe);
            }
            document.body.insertBefore(shadowDiv, document.body.firstChild); //遮罩层加入文档
            //弹出框
            var styleStr1 = 'display:block;position:fixed;_position:absolute;left:' + (winSize.windowWidth / 2 - 125) + 'px;top:' + (winSize.windowHeight / 2 - 70) + 'px;_top:' + (winSize.windowHeight / 2 + top - 150) + 'px;'; //弹出框的位置
            var alertBox = document.createElement('div');
            var alertTitle = document.createElement('div');
            alertTitle.id = 'alertTitle';
            alertBox.id = 'alertMsg';
            alertBox.style.cssText = styleStr1;
            //创建弹出框里面的内容P标签
            var alertMsg_info = document.createElement('P');
            alertMsg_info.id = 'alertMsg_info';
            alertMsg_info.innerHTML = msg;
            alertTitle.innerHTML = '提示信息!';
            alertBox.appendChild(alertTitle);
            alertBox.appendChild(alertMsg_info);
            //创建按钮
            var styleStr2 = 'display:block;position:fixed;_position:absolute;left:' + (winSize.windowWidth / 2 - 125) + 'px;top:' + (winSize.windowHeight / 2 + 40) + 'px;_top:' + (winSize.windowHeight / 2 + top - 150) + 'px;'; //弹出框的位置
            var alertBottom = document.createElement('div');
            alertBottom.id = 'alertBottom';
            alertBottom.style.cssText = styleStr2;
            if (mode === 1) {
                var btn1 = document.createElement('a');
                btn1.id = 'alertMsg_btn1';
                btn1.href = 'javas' + 'cript:void(0)';
                btn1.innerHTML = '<cite>确定</cite>';
                btn1.onclick = function () {
                    document.body.removeChild(alertBox);
                    document.body.removeChild(shadowDiv);
                    document.body.removeChild(alertBottom);
                    //document.getElementById("logout").click();
                    return true;
                };
                alertBottom.appendChild(btn1);
                var btn2 = document.createElement('a');
                btn2.id = 'alertMsg_btn2';
                btn2.href = 'javas' + 'cript:void(0)';
                btn2.innerHTML = '<cite>取消</cite>';
                btn2.onclick = function () {
                    document.body.removeChild(alertBox);
                    document.body.removeChild(shadowDiv);
                    document.body.removeChild(alertBottom);
                    return false;
                };
            } else {
                var btn2 = document.createElement('a');
                btn2.id = 'alertMsg_btn2';
                btn2.href = 'javas' + 'cript:void(0)';
                btn2.innerHTML = '<cite>确定</cite>';
                btn2.onclick = function () {
                    document.body.removeChild(alertBox);
                    document.body.removeChild(shadowDiv);
                    document.body.removeChild(alertBottom);
                    return false;
                };
            }
            alertBottom.appendChild(btn2);
            document.body.appendChild(alertBox);
            document.body.appendChild(alertBottom);

        }
        function confirmMsg() {
            if (alertMsg("测试", 1)) {
                alert("点击了确定");
            } else {
                alert("点击了取消");
            }
        }
    </script>
</head>
<body>

<input type="button" value="Test the alert"
       onclick="return confirmMsg('test confirm');">

</body>
</html>

为什么一点botton就直接运行了false啊??

5个回答

直接断点调试一下

目测,alertMsg是异步执行的,你需要将它的onclick暴露出来,把你的确定取消的判断写在onclick里面。

yvhkidt1221
yvhkidt1221 那有什么方法可以把它改成同步的么?在判断确定的时候需要执行不同的步骤啊、、
大约 5 年之前 回复

alertMsg没有return,默认返回的undefined,对于if来说是false

danielinbiti
danielinbiti 回复yvhkidt1221: /** * 回调函数测试方法 * * @param callback * 被回调的方法 */ function testCallback(callback) { alert('come in!'); callback(); } /** * 被回调的函数 */ function a() { alert('a'); } /** * 开始测试方法 */ function start() { testCallback(a); }
大约 5 年之前 回复
yvhkidt1221
yvhkidt1221 就是想模拟一个自定义的弹窗而已、、然后现在遇到了在确认的时候需要执行不同的方法就在想有没有方法可以判断我点击的事件再执行方法。渣渣一枚、、求指教。
大约 5 年之前 回复
danielinbiti
danielinbiti 回复yvhkidt1221: 。。。你这函数的功能要干什么。为什么异步是放在另一个元素的单击事件上呢?我觉得无比混乱
大约 5 年之前 回复
yvhkidt1221
yvhkidt1221 回复danielinbiti: 啊、、所以才是异步的。那要怎么让alertMsg返回判断呢?
大约 5 年之前 回复
danielinbiti
danielinbiti 回复yvhkidt1221: 那是onclick的绑定的事件函数,和当前执行的函数没任何关系。
大约 5 年之前 回复
yvhkidt1221
yvhkidt1221 回复danielinbiti: (⊙o⊙)…不是,我说的是在alertMsg里面的btn1跟btn2的onclick里面的return。
大约 5 年之前 回复
danielinbiti
danielinbiti 回复yvhkidt1221: onclick的return的是confirmMsg的返回值。和函数内部的return有什么关系呢
大约 5 年之前 回复
yvhkidt1221
yvhkidt1221 那我在btn1的onclick里面return的值就是没用的么??
大约 5 年之前 回复

你这个是层模拟的,和系统的alert不一样,无法挂起js代码的执行。需要回掉函数,再点击你的按钮时执行回掉函数做需要的操作

showbo
支付宝加好友偷能量挖 回复yvhkidt1221: 看发出来的代码,要居于回调。。
大约 5 年之前 回复
yvhkidt1221
yvhkidt1221 大神、、求具体的指导!!回调函数什么的不怎么会用啊、、
大约 5 年之前 回复

帮你大概改了下。

 <html>
<head><meta http-equiv="content-type" content="text/html;charset=gb2312" />
    <title>测试alertMsg</title>
    <link href="css/alertMsg.css" rel="stylesheet" type="text/css"/>
    <script type="text/javascript">
    //增加callback回调
        function alertMsg(msg, mode,callback) { //mode为空,即只有一个确认按钮,mode为1时有确认和取消两个按钮
            msg = msg || '';
            mode = mode || 0;
            var top = document.body.scrollTop || document.documentElement.scrollTop;
            var isIe = (document.all) ? true : false;
            var isIE6 = isIe && !window.XMLHttpRequest;
            var sTop = document.documentElement.scrollTop || document.body.scrollTop;
            var sLeft = document.documentElement.scrollLeft || document.body.scrollLeft;
            var winSize = function () {
                var xScroll, yScroll, windowWidth, windowHeight, pageWidth, pageHeight;
                // innerHeight获取的是可视窗口的高度,IE不支持此属性
                if (window.innerHeight && window.scrollMaxY) {
                    xScroll = document.body.scrollWidth;
                    yScroll = window.innerHeight + window.scrollMaxY;
                } else if (document.body.scrollHeight > document.body.offsetHeight) { // all but Explorer Mac
                    xScroll = document.body.scrollWidth;
                    yScroll = document.body.scrollHeight;
                } else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
                    xScroll = document.body.offsetWidth;
                    yScroll = document.body.offsetHeight;
                }

                if (self.innerHeight) {    // all except Explorer
                    windowWidth = self.innerWidth;
                    windowHeight = self.innerHeight;
                } else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
                    windowWidth = document.documentElement.clientWidth;
                    windowHeight = document.documentElement.clientHeight;
                } else if (document.body) { // other Explorers
                    windowWidth = document.body.clientWidth;
                    windowHeight = document.body.clientHeight;
                }

                // for small pages with total height less then height of the viewport
                if (yScroll < windowHeight) {
                    pageHeight = windowHeight;
                } else {
                    pageHeight = yScroll;
                }

                // for small pages with total width less then width of the viewport
                if (xScroll < windowWidth) {
                    pageWidth = windowWidth;
                } else {
                    pageWidth = xScroll;
                }

                return {
                    'pageWidth': pageWidth,
                    'pageHeight': pageHeight,
                    'windowWidth': windowWidth,
                    'windowHeight': windowHeight
                }
            } ();
            //alert(winSize.pageWidth);
            //遮罩层
            var styleStr = 'top:0;left:0;position:absolute;z-index:10000;background:#666;width:' + winSize.pageWidth + 'px;height:' + (winSize.pageHeight + 30) + 'px;';
            styleStr += (isIe) ? "filter:alpha(opacity=80);" : "opacity:0.8;"; //遮罩层DIV
            var shadowDiv = document.createElement('div'); //添加阴影DIV
            shadowDiv.style.cssText = styleStr; //添加样式
            shadowDiv.id = "shadowDiv";
            //如果是IE6则创建IFRAME遮罩SELECT
            if (isIE6) {
                var maskIframe = document.createElement('iframe');
                maskIframe.style.cssText = 'width:' + winSize.pageWidth + 'px;height:' + (winSize.pageHeight + 30) + 'px;position:absolute;visibility:inherit;z-index:-1;filter:alpha(opacity=0);';
                maskIframe.frameborder = 0;
                maskIframe.src = "about:blank";
                shadowDiv.appendChild(maskIframe);
            }
            document.body.insertBefore(shadowDiv, document.body.firstChild); //遮罩层加入文档
            //弹出框
            var styleStr1 = 'display:block;position:fixed;_position:absolute;left:' + (winSize.windowWidth / 2 - 125) + 'px;top:' + (winSize.windowHeight / 2 - 70) + 'px;_top:' + (winSize.windowHeight / 2 + top - 150) + 'px;'; //弹出框的位置
            var alertBox = document.createElement('div');
            var alertTitle = document.createElement('div');
            alertTitle.id = 'alertTitle';
            alertBox.id = 'alertMsg';
            alertBox.style.cssText = styleStr1;
            //创建弹出框里面的内容P标签
            var alertMsg_info = document.createElement('P');
            alertMsg_info.id = 'alertMsg_info';
            alertMsg_info.innerHTML = msg;
            alertTitle.innerHTML = '提示信息!';
            alertBox.appendChild(alertTitle);
            alertBox.appendChild(alertMsg_info);
            //创建按钮
            var styleStr2 = 'display:block;position:fixed;_position:absolute;left:' + (winSize.windowWidth / 2 - 125) + 'px;top:' + (winSize.windowHeight / 2 + 40) + 'px;_top:' + (winSize.windowHeight / 2 + top - 150) + 'px;'; //弹出框的位置
            var alertBottom = document.createElement('div');
            alertBottom.id = 'alertBottom';
            alertBottom.style.cssText = styleStr2;
            if (mode === 1) {
                var btn1 = document.createElement('a');
                btn1.id = 'alertMsg_btn1';
                btn1.href = 'javas' + 'cript:void(0)';
                btn1.innerHTML = '<cite>确定</cite>';
                btn1.onclick = function () {
                    if (typeof callback == 'function') callback(this);////传递了回调则执行回调,将按钮作为回调参数
                    document.body.removeChild(alertBox);
                    document.body.removeChild(shadowDiv);
                    document.body.removeChild(alertBottom);
                    //document.getElementById("logout").click();
                    return true;
                };
                alertBottom.appendChild(btn1);
                var btn2 = document.createElement('a');
                btn2.id = 'alertMsg_btn2';
                btn2.href = 'javas' + 'cript:void(0)';
                btn2.innerHTML = '<cite>取消</cite>';
                btn2.onclick = function () {
                    if (typeof callback == 'function') callback(this); ////传递了回调则执行回调,将按钮作为回调参数
                    document.body.removeChild(alertBox);
                    document.body.removeChild(shadowDiv);
                    document.body.removeChild(alertBottom);
                    return false;
                };
            } else {
                var btn2 = document.createElement('a');
                btn2.id = 'alertMsg_btn2';
                btn2.href = 'javas' + 'cript:void(0)';
                btn2.innerHTML = '<cite>确定</cite>';
                btn2.onclick = function () {
                    if (typeof callback == 'function') callback(this); ////传递了回调则执行回调,将按钮作为回调参数
                    document.body.removeChild(alertBox);
                    document.body.removeChild(shadowDiv);
                    document.body.removeChild(alertBottom);
                    return false;
                };
            }
            alertBottom.appendChild(btn2);
            document.body.appendChild(alertBox);
            document.body.appendChild(alertBottom);

        }
        function confirmMsg() {
            alertMsg("测试", 1, function (btn) { //将点击的按钮作为回调函数的参数
                var text = btn.innerHTML.replace(/<[^>]+>/g, ''); //去掉所有html标签
                alert('点击了“' + text + '”按钮');
            });
        }
    </script>
</head>
<body>

<input type="button" value="Test the alert"
       onclick="confirmMsg('test confirm');">

</body>
</html>
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