Chartjs-Why doesn't my donut chart, created with Chart.js, appear?

This is because, you are trying to get other canvas elements, which are not present in reformaTrabalhista.html.

You should better get canvas­‘s context, for all the canvases, like so :

var canvas = document.getElementById("canvas-id-here");
var ctx = canvas && canvas.getContext("2d");

and define the chart instance, as such :

chart-variable-name = ctx && new Chart(ctx).Doughnut(data, options);

Here is the modified version of mycharts.js – https://kopy.io/0HiRj