[Chartjs]-Using Chart.js – Creating Legend for Doughnut Chart

Where you are trying to use ‘helpers’ and ‘canvas’ you do not have scope for them.

Helpers refers to Chartjs helpers, this can be easily added by creating

var helpers = Chart.helpers

Canvas refers to you race variables canvas so just add

race.chart.canvas.parentNode.parentNode.appendChild(legendHolder.firstChild);

here is a fiddle with it working