Simple JavaScript Date Calculator

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Save this code into "*.HTA" extension (ex. "DateCalc.hta"): 

<table align='center' cellspacing='2px'><tr> <td align='left' id='dd1'></td><td id='mm1'></td><td id='yy1'></td> <td><div style='font-family:arial;font-weight:bold;font-size:12pt'>TO</div></td> <td id='dd2'></td><td id='mm2'></td><td align='right' id='yy2'></td> <tr><td colspan='7'><input type='text' ReadOnly style='width:100%;' id='result' value='Total 0 day(s)'> </td></tr></table> <script language='JavaScript'> var e="getElementById" var h="innerHTML" var i="selectedIndex" build("d",1,31); build("m",1,12); build("y",1900,2099); var dt=new(Date); d1[i]=(dt.getDate()-1); m1[i]=dt.getMonth(); y1[i]=(dt.getFullYear()-1900); d2[i]=d1[i];m2[i]=m1[i];y2[i]=y1[i]; function count(){ from=new Date((y1[i]+1900),m1[i],(d1[i]+1)); to=new Date((y2[i]+1900),m2[i],(d2[i]+1)); result.value="Total "+Math.round((to-from)/(1000*60*60*24))+" day(s)";} function build(n,c,w){ var bdy="onchange='count()'>"; while(c<=w){bdy=bdy+"<option>"+c+"</option>";c=(c+1)}; document[e](n+n+"1")[h]="<select id='"+n+"1' "+bdy+"</select>"; document[e](n+n+"2")[h]="<select id='"+n+"2' "+bdy+"</select>";} </script>