用javascript父窗口控制只弹出一个子窗口_javascript技巧

近来网上经常流传一些关于如何在父窗口控制只弹出一个子窗口 问题，我查看了一些，大部分都是只能解决部分或者很麻烦，还不算完美。比如有人是实现的这样，使用的是Cookie，以下是例子。 
主页上做了一个弹出窗口，如何使其只弹出一次，返回主页时不再弹出了。 
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<script> <br>window.open("http://www.yeboss.com.cn","yeboss","width=300,height=400") <br></script> 
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cookie 
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<script> <br><br><!-- Begin <br>var expDays = 1; // number of days the cookie should last <br><br>var page = "only-popup-once.html"; <br>var windowprops = "width=300,height=200,location=no,toolbar=no,menubar=no,scrollbars=no,resizable=yes"; <br><br>function GetCookie (name) { <br>var arg = name + "="; <br>var alen = arg.length; <br>var clen = document.cookie.length; <br>var i = 0; <br>while (i < clen) { <br>var j = i + alen; <br>if (document.cookie.substring(i, j) == arg) <br>return getCookieVal (j); <br>i = document.cookie.indexOf(" ", i) + 1; <br>if (i == 0) break; <br>} <br>return null; <br>} <br>function SetCookie (name, value) { <br>var argv = SetCookie.arguments; <br>var argc = SetCookie.arguments.length; <br>var expires = (argc > 2) ? argv[2] : null; <br>var path = (argc > 3) ? argv[3] : null; <br>var domain = (argc > 4) ? argv[4] : null; <br>var secure = (argc > 5) ? argv[5] : false; <br>document.cookie = name + "=" + escape (value) + <br>((expires == null) ? "" : ("; expires=" + expires.toGMTString())) + <br>((path == null) ? "" : ("; path=" + path)) + <br>((domain == null) ? "" : ("; domain=" + domain)) + <br>((secure == true) ? "; secure" : ""); <br>} <br>function DeleteCookie (name) { <br>var exp = new Date(); <br>exp.setTime (exp.getTime() - 1); <br>var cval = GetCookie (name); <br>document.cookie = name + "=" + cval + "; expires=" + exp.toGMTString(); <br>} <br>var exp = new Date(); <br>exp.setTime(exp.getTime() + (expDays*24*60*60*1000)); <br>function amt(){ <br>var count = GetCookie(&#146;count&#146;) <br>if(count == null) { <br>SetCookie(&#146;count&#146;,&#146;1&#146;) <br>return 1 <br>} <br>else { <br>var newcount = parseInt(count) + 1; <br>DeleteCookie(&#146;count&#146;) <br>SetCookie(&#146;count&#146;,newcount,exp) <br>return count <br> } <br>} <br>function getCookieVal(offset) { <br>var endstr = document.cookie.indexOf (";", offset); <br>if (endstr == -1) <br>endstr = document.cookie.length; <br>return unescape(document.cookie.substring(offset, endstr)); <br>} <br><br>function checkCount() { <br>var count = GetCookie(&#146;count&#146;); <br>if (count == null) { <br>count=1; <br>SetCookie(&#146;count&#146;, count, exp); <br><br>window.open(page, "", windowprops); <br><br>} <br>else { <br>count++; <br>SetCookie(&#146;count&#146;, count, exp); <br> } <br>} <br>// End --> <br></script> 


 
这个是网上随便摘的一个例子，是不是感觉很多也很难看懂呢，下面我给大家说一种新方法，保证好看好使。

<script> <br><!-- Copyright fenggang at 2007/3/23 <br>var w=null; <br>function MM_openBrWindow(theURL,winName,features) { //v2.0 <br> if(w!=undefined&&isOpen()){ <br> w.close(); <br> } <br> w=window.open("",winName,features); <br> w.location.replace(theURL); <br>} <br>function isOpen() <br>{ <br> try <br> { <br> w.document; <br> return true; <br> } <br> catch(ex) <br> {} <br><br> return false; <br>} <br>//--> <br></script>
这个MM_openBrWindow（）函数名是在Dreamweaver中常用的弹出窗口函数名，将这段代码放进页面里
然后再做弹出窗口就只能探出一个窗口了，以上是精髓部分，下面是完整的一个测试页的代码，试试看吧。

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<script> <br><!-- Copyright fenggang at 2007/3/23 <br>var w=null; <br>function MM_openBrWindow(theURL,winName,features) { //v2.0 <br> if(w!=undefined&&isOpen()){ <br> w.close(); <br> } <br> w=window.open("",winName,features); <br> w.location.replace(theURL); <br>} <br>function isOpen() <br>{ <br> try <br> { <br> w.document; <br> return true; <br> } <br> catch(ex) <br> {} <br><br> return false; <br>} <br>//--> <br></script>


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