Chart.js number format

Put tooltips in 'option' like this:

options: {
  tooltips: {
      callbacks: {
          label: function(tooltipItem, data) {
              return tooltipItem.yLabel.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
          }
      }
  }
}

Reference from https://github.com/chartjs/Chart.js/pull/160.

Existing solutions did not to work for me in Chart.js v2.5. The solution I found:

options: {
            scales: {
                yAxes: [{
                    ticks: {
                        callback: function (value) {
                            return numeral(value).format('$ 0,0')
                        }
                    }
                }]
            }
        }

I used numeral.js, but you can use the addCommas function proposed by Yacine, or anything else.

There is no built-in functionality for number formatting in Javascript. I found the easiest solution to be the addCommas function on this page.

Then you just have to modify your tooltipTemplate parameter line from your Chart.defaults.global to something like this:

tooltipTemplate: "<%= addCommas(value) %>"

Charts.js will take care of the rest.

Here's the addCommas function:

function addCommas(nStr)
{
    nStr += '';
    x = nStr.split('.');
    x1 = x[0];
    x2 = x.length > 1 ? '.' + x[1] : '';
    var rgx = /(\d+)(\d{3})/;
    while (rgx.test(x1)) {
        x1 = x1.replace(rgx, '$1' + ',' + '$2');
    }
    return x1 + x2;
}