Chartjs Quickref

Chart.js Quick Reference (v4.5.1)

Copy-paste snippets for common Chart.js patterns.

Data Formatting

Currency Labels

ticks: {
  callback: (value) => '$' + value.toLocaleString()
}

Percentage Labels

ticks: {
  callback: (value) => value + '%'
}

Abbreviated Numbers (1K, 1M)

ticks: {
  callback: (value) => {
    if (value >= 1000000) return (value / 1000000).toFixed(1) + 'M';
    if (value >= 1000) return (value / 1000).toFixed(1) + 'K';
    return value;
  }
}

Date/Time Labels

// Requires: import 'chartjs-adapter-date-fns'; (or luxon, moment)
scales: {
  x: {
    type: 'time',
    time: {
      unit: 'day',
      displayFormats: { day: 'MMM d' }
    }
  }
}

Common Configurations

Hide Legend

plugins: { legend: { display: false } }

Hide Tooltip

plugins: { tooltip: { enabled: false } }

Hide Title

plugins: { title: { display: false } }

Start Y-axis at Zero

scales: { y: { beginAtZero: true } }

Set Axis Range

scales: { y: { min: 0, max: 100 } }

Horizontal Bar Chart

type: 'bar',
options: { indexAxis: 'y' }

Disable Animation

animation: false

Stacked Bar/Line Chart

scales: {
  x: { stacked: true },
  y: { stacked: true }
}

Styling

Chart.js Default Palette

const colors = [
  'rgb(255, 99, 132)',   // red
  'rgb(54, 162, 235)',   // blue
  'rgb(255, 206, 86)',   // yellow
  'rgb(75, 192, 192)',   // teal
  'rgb(153, 102, 255)',  // purple
  'rgb(255, 159, 64)'    // orange
];

Semi-Transparent Backgrounds

backgroundColor: 'rgba(54, 162, 235, 0.5)',
borderColor: 'rgb(54, 162, 235)'

Hide Grid Lines

scales: {
  x: { grid: { display: false } },
  y: { grid: { display: false } }
}

Custom Font

Chart.defaults.font.family = "'Inter', sans-serif";
Chart.defaults.font.size = 14;

Responsiveness

Fill Container

options: {
  responsive: true,
  maintainAspectRatio: false
}

<div style="height: 400px;">
  <canvas id="myChart"></canvas>
</div>

Fixed Aspect Ratio

options: {
  responsive: true,
  aspectRatio: 2  // width:height = 2:1
}

Square Chart

options: { aspectRatio: 1 }

Dynamic Updates

Update Data

chart.data.datasets[0].data = [1, 2, 3, 4, 5];
chart.update();

Update Without Animation

chart.update('none');

Add Data Point

chart.data.labels.push('New Label');
chart.data.datasets[0].data.push(42);
chart.update();

Remove Data Point

chart.data.labels.pop();
chart.data.datasets[0].data.pop();
chart.update();

Destroy Chart

chart.destroy();

Event Handling

Click Handler

options: {
  onClick: (event, elements) => {
    if (elements.length > 0) {
      const index = elements[0].index;
      console.log('Clicked:', chart.data.labels[index]);
    }
  }
}

Export as Image

const imageUrl = chart.toBase64Image();

Tree-Shaking Imports

Bar Chart

import { Chart, BarController, BarElement, CategoryScale, LinearScale } from 'chart.js';
Chart.register(BarController, BarElement, CategoryScale, LinearScale);

Line Chart

import { Chart, LineController, LineElement, PointElement, CategoryScale, LinearScale } from 'chart.js';
Chart.register(LineController, LineElement, PointElement, CategoryScale, LinearScale);

Pie/Doughnut Chart

import { Chart, PieController, ArcElement, Legend, Tooltip } from 'chart.js';
Chart.register(PieController, ArcElement, Legend, Tooltip);
// Use DoughnutController for doughnut charts

With Legend and Tooltip

import { Legend, Tooltip } from 'chart.js';
Chart.register(Legend, Tooltip);

Quick Start Templates

Minimal Bar Chart

new Chart(ctx, {
  type: 'bar',
  data: {
    labels: ['A', 'B', 'C'],
    datasets: [{ data: [10, 20, 30] }]
  }
});

Minimal Line Chart

new Chart(ctx, {
  type: 'line',
  data: {
    labels: ['Jan', 'Feb', 'Mar'],
    datasets: [{ data: [10, 20, 15] }]
  }
});

Minimal Pie Chart

new Chart(ctx, {
  type: 'pie',
  data: {
    labels: ['Red', 'Blue', 'Yellow'],
    datasets: [{ data: [30, 50, 20] }]
  }
});

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