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Math with no javascript. I don't understand it.


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<html>
<head>
<style>
#table.my-table{
border-color: #FFCC00 #FFCC00 #FFCC00 #FFCC00; <!-- #BFBFBF #5A5A5A #5A5A5A #BFBFBF; -->
bgcolor: #FFCC00;
border-style: solid;
border-width: 10px;
text-align: left;
border-collapse: separate;
border-spacing: 2px;	
}
table.my-table tr{		
}
.my-table td{			
padding:2px 7px;		
border:1px solid;
border-color:#5A5A5A #BFBFBF #BFBFBF #5A5A5A ;
}
</style>
</head>
<body>
<FORM>
<center>
<table BORDER=4 BGCOLOR="#bfe3fe" >
 <tr>
 <td ALIGN=CENTER VALIGN=CENTER COLSPAN="7"><center><h2>Temperature Conversion Calculator</h2></center>
 </td>
 </tr>
 <tr>
 <td ALIGN=CENTER>Fahrenheit</td>
 <td ALIGN=CENTER>Celsius</td>
 <td ALIGN=CENTER>Kelvin</td>
 <td><center><INPUT TYPE="Reset" NAME="Reset" VALUE="Reset"></center></td>
 </tr>
 <tr>
 <td><center><INPUT TYPE="text" NAME="F" VALUE="" SIZE="6" MAXLENGTH="6" onchange="eval('C.value = ' + this.form.C_expr.value);eval('K.value = ' + this.form.K_expr.value)">
			 <INPUT TYPE="hidden" NAME="F_expr" VALUE="(Math.round(((212-32)/100 * C.value + 32)*100))/100;">
			 <INPUT TYPE="hidden" NAME="F_expr2" VALUE="(Math.round(((212-32)/100 *(K.value - 273) + 32)*100))/100; "></center></td>
 <td><center><INPUT TYPE="text" NAME="C" VALUE="" SIZE="6" MAXLENGTH="6" onchange="eval('F.value = ' + this.form.F_expr.value);eval('K.value = ' + this.form.K_expr.value)">
			 <INPUT TYPE="hidden" NAME="C_expr" VALUE="(Math.round((100/(212-32) * (F.value - 32))*100))/100"> <INPUT TYPE="hidden" NAME="C_expr2" VALUE="(Math.round(K.value - 273))"></center></td>
 <td><center><INPUT TYPE="text" NAME="K" VALUE="" SIZE="6" MAXLENGTH="6" onchange="eval('F.value = ' + this.form.F_expr2.value);eval('C.value = ' + this.form.C_expr2.value)">
			 <INPUT TYPE="hidden" NAME="K_expr" VALUE="(Math.round((100/(212-32) * (F.value - 32))*100))/100 + 273"></center></td>
 <td><center><INPUT TYPE="button" NAME="Reset" VALUE="Calculate"></center></td>
 </tr>
</table>
</center>
</FORM>
</body>
</html>

I was looking for a program to do length, volume, weight and temperature conversions for my web site. I found the first 3 written in Javascript. I tried to modify it to include temperature with no success. Then I discovered one for temperature and modified the look to match what I already had.

 

But I have never seen computations done with html alone. I cannot find an explanation anywhere. Everything I can find says “onchange designates a Javascript to run…”

 

Can you point me to an explanation of :

 

onchange="eval('C.value = ' + this.form.C_expr.value);eval('K.value = ' + this.form.K_expr.value)">

 

and

 

VALUE="(Math.round(((212-32)/100 * C.value + 32)*100))/100;">

 

I understand the math. But I can’t find “eval, this form, C expr.value” used with onchange. And I can’t find “Math.round” used with VALUE.

Edited by crmamx

But I have never seen computations done with html alone. I cannot find an explanation anywhere. Everything I can find says “onchange designates a Javascript to run…”

Because it can't. HTML is purely markup. It cannot do math.

 

Can you point me to an explanation of :

 

onchange="eval('C.value = ' + this.form.C_expr.value);eval('K.value = ' + this.form.K_expr.value)">

 

and

 

VALUE="(Math.round(((212-32)/100 * C.value + 32)*100))/100;">

 

I understand the math. But I can’t find “eval, this form, C expr.value” used with onchange. And I can’t find “Math.round” used with VALUE.

 

What are you confused about? The functions you use in an onchange are irrelevant to how they work.

Many thanks. I now have a totally new outlook on life........well, almost.

 

I can usually get the job done although I certainly am not an advanced coder. I have called functions but never realized you could execute javascript without being inside <script></script>.

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