How to store fraction value in text field and then convert it to decimal

First let us look at what your input value could look like.

A whole number like 64 or "1)".

A fraction string like  "1/4".

A whole number plus a fraction string like "10 3/4" or "10-3/4".

With so many possible input variations I would look at using the Regular Expression object to identify which variation of the various inputs I have to process and then do the math. I would also use the "switch" statement so I only run the one conversion process that is needed and skip the other 2 options. I would also include a way to deal with a bad input value.

A possible function:

function ConvertFrac2Dec(cString)
{
// Convert a string of numberic values consisting of a whole number and fraciton string to a decimal number;
// invalid input will result in a return of a null value;

// convert numeric string with a fraction to a decimal number;
var nDecimal = null;
switch(true) {
  case /^(\d*)$/.test(cString) :
   nDecimal = RegExp.$1;
  break;

  case /^(\d*)\/(\d*)$/.test(cString):
   nDecimal = RegExp.$1 / RegExp.$2
  break;

  case /^(\d*)[ -](\d*)\/(\d*)$/.test(cString):
   nDecimal = Number(RegExp.$1) + Number((RegExp.$2 / RegExp.$3));
  break;

  default:
   // all other strings;
   nDecimal = null
  break;
}

return nDecimal;
} // end ConvertFrac2Dec function;

The custom calculation for the result field could be:

var nResult = ConvertFrac2Dec(this.getField("FractionString").value);

if(nResult == null)

{

app.alert("Invlid input for conversion from fractional string to decimal value", 1, 0);

event.vaue = "";

} else {

event.value = nResult;

}

You will have to adjust the input field name as needed.

What JavaScript code do you use?