Colorize negative/positive numbers (jQuery)

Question

I'd like to color numbers in a table for better readability: 

green for positive (+00.00); red for negative (-00.00) and; black for default case (no sign)

Many thanks!

Answer 1

Firstly, the best way to do this if the numbers are static is on the serverside. Assign a class based on value:

<td class="positive">+34</td>
<td class-"negative">-33</td>

with:

td { color: black; }
td.positive { color: green; }
td.negative { color: red; }

(or be more selective if you need to be).

But if you must do this on the client, I might suggest:

$("td").each(function() {
  var text = $(this).text();
  if (/[+-]?\d+(\.\d+)?/.test(text)) {
    var num = parseFloat(text);
    if (num < 0) {
      $(this).addClass("negative");
    } else if (num > 0) {
      $(this).addClass("positive");
    }

  }
});

You may need to adjust the regular expression depending on what kinds of numbers you want to catch (eg 1.2e11 or 3,456).

Why the regex and not just parseFloat()? Because:

parseFloat("34 widgets");

returns 34. If this is fine then use that and skip the regex test.

Answer 2

Here ya go:

$(document).ready( function() {

  // the following will select all 'td' elements with class "of_number_to_be_evaluated"
  // if the TD element has a '-', it will assign a 'red' class, and do the same for green.

  $("td.of_number_to_be_evaluated:contains('-')").addClass('red');
  $("td.of_number_to_be_evaluated:contains('+')").addClass('green');
}

Then use CSS to style the input elements:

td.red {
  color: red;
}

td.green {
  color: green;
}

Answer 3

The css:

.pos { color:green; }
.neg { color:red; }

The markup

<table>
  <tr><td>+11.11</td><td>-24.88</td><td>00.00</td></tr>
  <tr><td>-11.11</td><td>4.88</td><td>+16.00</td></tr>
</table>

The code

$('td').each(function() {
  var val = $(this).text(), n = +val;
  if (!isNaN(n) && /^\s*[+-]/.test(val)) {
    $(this).addClass(val >= 0 ? 'pos' : 'neg')
  }
})