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skills/smithery.ai/chartjs-chart-types

chartjs-chart-types

SKILL.md

Chart.js Chart Types (v4.5.1)

Complete guide to all Chart.js chart types, their configuration, and dataset properties.

Available Chart Types

Type Description Use Case
line Line chart Trends over time
bar Bar chart Comparing categories
pie Pie chart Parts of a whole
doughnut Doughnut chart Parts of a whole with center
radar Radar/spider chart Multivariate data comparison
polarArea Polar area chart Cyclical data
bubble Bubble chart Three dimensions
scatter Scatter plot Correlation analysis

Line Chart

Show trends and changes over time:

new Chart(ctx, {
  type: 'line',
  data: {
    labels: ['Jan', 'Feb', 'Mar', 'Apr', 'May'],
    datasets: [{
      label: 'Sales',
      data: [65, 59, 80, 81, 56],
      fill: false,
      borderColor: 'rgb(75, 192, 192)',
      tension: 0.1  // 0 = straight lines, 0.4 = curved
    }]
  }
});

Key Line Properties

Property Type Description
tension number Bezier curve tension (0-1)
fill boolean/string Fill area under line
stepped boolean/string Stepped line interpolation
borderDash number[] Dashed line pattern
pointRadius number Data point size
pointStyle string Point shape (circle, rect, triangle, etc.)
spanGaps boolean Connect over null values

Vertical Line Chart

Flip axes with indexAxis:

options: {
  indexAxis: 'y'  // Vertical line chart
}

Bar Chart

Compare discrete categories:

new Chart(ctx, {
  type: 'bar',
  data: {
    labels: ['Red', 'Blue', 'Yellow', 'Green'],
    datasets: [{
      label: 'Votes',
      data: [12, 19, 3, 5],
      backgroundColor: [
        'rgba(255, 99, 132, 0.5)',
        'rgba(54, 162, 235, 0.5)',
        'rgba(255, 206, 86, 0.5)',
        'rgba(75, 192, 192, 0.5)'
      ],
      borderWidth: 1
    }]
  },
  options: {
    scales: {
      y: { beginAtZero: true }
    }
  }
});

Key Bar Properties

Property Type Description
barThickness number/'flex' Bar width in pixels
barPercentage number Bar width relative to category (0-1)
categoryPercentage number Category width (0-1)
borderRadius number/object Rounded corners
borderSkipped string Which border to skip

Horizontal Bar Chart

options: {
  indexAxis: 'y'  // Makes bars horizontal
}

Stacked Bar Chart

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

Pie & Doughnut Charts

Show proportional data:

// Pie chart
new Chart(ctx, {
  type: 'pie',
  data: {
    labels: ['Red', 'Blue', 'Yellow'],
    datasets: [{
      data: [300, 50, 100],
      backgroundColor: ['#ff6384', '#36a2eb', '#ffce56']
    }]
  }
});

// Doughnut chart
new Chart(ctx, {
  type: 'doughnut',
  data: { /* same as pie */ },
  options: {
    cutout: '50%'  // Size of center hole
  }
});

Key Pie/Doughnut Properties

Property Type Description
cutout number/string Center hole size (doughnut)
rotation number Starting angle (degrees)
circumference number Arc sweep (degrees)
offset number Arc offset on hover
hoverOffset number Offset when hovering

Semi-Circle Chart

options: {
  rotation: -90,
  circumference: 180
}

Radar Chart

Compare multiple variables across categories:

new Chart(ctx, {
  type: 'radar',
  data: {
    labels: ['Speed', 'Power', 'Defense', 'Stamina', 'Agility'],
    datasets: [{
      label: 'Player A',
      data: [65, 59, 90, 81, 56],
      fill: true,
      backgroundColor: 'rgba(255, 99, 132, 0.2)',
      borderColor: 'rgb(255, 99, 132)',
      pointBackgroundColor: 'rgb(255, 99, 132)'
    }, {
      label: 'Player B',
      data: [28, 48, 40, 19, 96],
      fill: true,
      backgroundColor: 'rgba(54, 162, 235, 0.2)',
      borderColor: 'rgb(54, 162, 235)'
    }]
  },
  options: {
    scales: {
      r: {
        angleLines: { display: true },
        suggestedMin: 0,
        suggestedMax: 100
      }
    }
  }
});

Polar Area Chart

Like pie but with equal angles, varying radius:

new Chart(ctx, {
  type: 'polarArea',
  data: {
    labels: ['Red', 'Green', 'Yellow', 'Grey', 'Blue'],
    datasets: [{
      data: [11, 16, 7, 3, 14],
      backgroundColor: [
        'rgba(255, 99, 132, 0.5)',
        'rgba(75, 192, 192, 0.5)',
        'rgba(255, 205, 86, 0.5)',
        'rgba(201, 203, 207, 0.5)',
        'rgba(54, 162, 235, 0.5)'
      ]
    }]
  }
});

Scatter Chart

Show correlation between two variables:

new Chart(ctx, {
  type: 'scatter',
  data: {
    datasets: [{
      label: 'Data Points',
      data: [
        { x: 10, y: 20 },
        { x: 15, y: 10 },
        { x: 20, y: 30 },
        { x: 25, y: 25 }
      ],
      backgroundColor: 'rgb(255, 99, 132)'
    }]
  },
  options: {
    scales: {
      x: { type: 'linear', position: 'bottom' },
      y: { type: 'linear' }
    }
  }
});

Bubble Chart

Three-dimensional data visualization:

new Chart(ctx, {
  type: 'bubble',
  data: {
    datasets: [{
      label: 'Dataset',
      data: [
        { x: 20, y: 30, r: 15 },  // r = bubble radius
        { x: 40, y: 10, r: 10 },
        { x: 30, y: 22, r: 25 }
      ],
      backgroundColor: 'rgba(255, 99, 132, 0.5)'
    }]
  },
  options: {
    aspectRatio: 1  // Square chart for bubbles
  }
});

Area Chart

Line chart with filled area:

new Chart(ctx, {
  type: 'line',
  data: {
    labels: ['Jan', 'Feb', 'Mar', 'Apr', 'May'],
    datasets: [{
      label: 'Revenue',
      data: [65, 59, 80, 81, 56],
      fill: true,  // Enable fill
      backgroundColor: 'rgba(75, 192, 192, 0.2)',
      borderColor: 'rgb(75, 192, 192)'
    }]
  }
});

Fill Options

Value Description
false No fill (default)
true Fill to origin
'origin' Fill to origin
'start' Fill to bottom
'end' Fill to top
'-1' Fill to previous dataset
'+1' Fill to next dataset

Mixed Charts

Combine multiple chart types:

new Chart(ctx, {
  type: 'bar',  // Base type
  data: {
    labels: ['Jan', 'Feb', 'Mar', 'Apr'],
    datasets: [
      {
        type: 'line',  // Override type for this dataset
        label: 'Trend',
        data: [50, 60, 70, 80],
        borderColor: 'rgb(255, 99, 132)',
        fill: false
      },
      {
        type: 'bar',  // Explicit bar type
        label: 'Sales',
        data: [40, 55, 65, 75],
        backgroundColor: 'rgba(54, 162, 235, 0.5)'
      }
    ]
  }
});

Drawing Order

Control which dataset renders on top:

datasets: [
  { label: 'Bars', order: 2 },  // Drawn first (behind)
  { label: 'Line', order: 1 }   // Drawn last (on top)
]

Data Structures

Standard Format

data: {
  labels: ['A', 'B', 'C'],
  datasets: [{
    data: [10, 20, 30]
  }]
}

Object Format

datasets: [{
  data: [
    { x: 'A', y: 10 },
    { x: 'B', y: 20 },
    { x: 'C', y: 30 }
  ]
}]

Parsed Data Format

datasets: [{
  data: [
    { id: 'Sales', value: 100 },
    { id: 'Revenue', value: 200 }
  ],
  parsing: {
    xAxisKey: 'id',
    yAxisKey: 'value'
  }
}]

Additional Resources

  • See references/dataset-properties.md for complete property reference
  • See examples/ for working HTML examples:
    • line-area-charts.html - Line charts with tension, area fills, stepped lines
    • bar-charts.html - Vertical, horizontal, stacked bars, and mixed bar+line
    • circular-charts.html - Pie, doughnut, semi-circle gauge, polar area, radar
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