mcUIControls - mcFormatNumber

The mcFormatNumber function is part of mcUITools.js - the purpose of this page is to test it.

Live demo - enter a value - mcFormatNumber( format, value, digits ) -
Value	Digits	Valid formats
Value	Digits	Default	fixed	exp	float	comas

1003.14	2	1003.14	1003.14	1.00e+3	1.0e+3	1,003.14
	1	1003.14	1003.1	1.0e+3	1e+3	1,003.1
	0	1003.14	1003	1e+3	not supported	1,003
3.14	2	3.14	3.14	3.14e+0	3.1	3.14
0.00005	4	0.00005	0.0001	5.0000e-5	0.00005000	0.0001
0.0000005	4	5e-7	0.0000	5.0000e-7	5.000e-7	0.0000

The format strings are case insensitive.
Any unrecognized format produces the default value
The comas only adds a single comma
The top line of the table is live, the lower lines show results for future test verification

When producing graphs, I wanted a way to add a comma to the tick labels. Since this is fairly complicated, and since javascript does not have a format command (method), I created this function.

For entered numbers, the default conversion is pretty good .. until the result of some division produces 8 (or more) digits of precision - then it is a disaster!

In addition, I strongly dislike software that produces some result and you simply have to accept it.

In use, the user can select the formatting type and number of digits.

The code

var mcFormatNumber = function( format, value, digits ){

  var formattedString = value.toString(); // this could be very long

  format = format.toLowerCase();

  if (format == "fixed" ) formattedString = value.toFixed(digits);
  if (format == "exp"   ) formattedString = value.toExponential(digits); // forces exponential notation 3.digits e+5

  if (format == "float" ) 
    if (digits > 0)       formattedString = value.toPrecision(digits);   // total number of significant digits
    else                  formattedString = "not supported";

  if (format == "comas") {
    formattedString = value.toFixed(digits);
    if (value > 1000) { // add only one coma
      var xx = Math.trunc(value / 1000);
      var yy = (value - xx*1000);
      var xyz = "000" + yy.toFixed(digits);
      var zz  = xyz.match(/\d{3}\.\d+/);    // force 3 digits
      if (zz==null) zz = xyz.match(/\d{3}$/);
      formattedString = xx.toFixed(0) + ',' + zz ;
    }
  }

  return formattedString ;
}

Author: Robert Clemenzi

mcUIControls - mcFormatNumber

The code

URL: http:// mc-computing.com / Languages / Javascript / mcUIControls / test / mcFormatNumber.html