Monday, 10 October 2011

Get Url Parameters using Javascript

            Nearly all server-side programming languages have built-in functions to retrieve querystring values of an URL. In web browsers you can access the querystring with client-side JavaScript, but there is no standard way to parse out the name/value pairs. So here is a function to return a parameter you specify. The following javascript code snippet facilitates Javascript's built in regular expressions to retrieve value of the key. Optionally, you can specify a default value to return when key does not exist.

<script language="javascript" type="text/javascript">
    function getParamValue(key, default_)
    {
        if (default_==null) default_="";
            key = key.replace(/[\[]/,"\\\[").replace(/[\]]/,"\\\]");
        var regex = new RegExp("[\\?&]"+key+"=([^&#]*)");
        var qs = regex.exec(window.location.href);
        if(qs == null)
            return default_;
        else
            return qs[1];
    }
    function GetUrl()
    {
        var a=getParamValue('a',' ');
        var b=getParamValue('b',' ');
        if(a!=' ' && b!=' ')
            alert("a: "+a+";  b: "+b);
    }
    </script>
</head>
<body onload="GetUrl();">
<body>

Tag: javascript, javascript function, query string, querysting in javascript, url parameters

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