samber / samber/chartjs-plugin-datasource-prometheus

Cannot read properties of null (reading 'addEventListener')

Open
#40 4 comments 1 reaction 0 assignees View on GitHub

Nobody has claimed this yet.

Dominant language
TypeScript
Stars
123
Forks
23
PR merge metrics
No merged PRs in 30d

Description

Hi, i have got the error in the console

import { useEffect, useRef } from "react";
import Chart from "chart.js/auto";
import "chartjs-adapter-date-fns";
import ChartDatasourcePrometheusPlugin from "chartjs-plugin-datasource-prometheus";
import "./styles.css";

export default function App() {
  const canvasRef = useRef<HTMLCanvasElement>(null);
  const chartRef = useRef<Chart | null>(null);

  useEffect(() => {
    if (canvasRef.current) {
      chartRef.current = new Chart(canvasRef.current, {
        type: "line",
        data: {
          datasets: [],
        },
        plugins: [ChartDatasourcePrometheusPlugin],
        options: {
          plugins: {
            "datasource-prometheus": {
              prometheus: {
                endpoint: "https://prometheus.demo.do.prometheus.io",
                baseURL: "/api/v1", // default value
              },
              query: "sum by (job) (go_gc_duration_seconds)",
              timeRange: {
                type: "relative",
                // from 1 hours ago to now
                start: -1 * 60 * 60 * 1000,
                end: 0,
              },
            },
          },
        },
      });
    }

    return () => {
      chartRef.current?.destroy();
    };
  }, []);

  return <canvas ref={canvasRef}></canvas>;
}

Playground:
https://codesandbox.io/p/sandbox/chartjs-prometheus-bug-4jq97s

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the error using the linked CodeSandbox and the React example in the issue body. Trace the plugin initialization around the reported addEventListener failure, then verify that the example creates the chart without the console error and can read the Prometheus data.

Written by the indexing model from the issue text.

Assessment

Tech stack
chart.js, prometheus, react, typescript
Domain
frontend, observability-sre
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
42/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.