301 lines
7.5 KiB
Markdown
301 lines
7.5 KiB
Markdown
# ASCII Bar Chart
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A dynamic, real-time ASCII-based vertical bar chart library that renders beautiful terminal-style visualizations using monospaced characters. Perfect for dashboards, monitoring tools, or any application that needs lightweight, text-based data visualization.
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## Features
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- 📊 **Real-time Updates**: Add data points dynamically and watch the chart animate
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- 📏 **Auto-scaling**: Y-axis automatically adjusts to show min/max values
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- 🔤 **Monospaced Rendering**: Uses 'X' characters in Courier font for clean visualization
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- 📱 **Responsive**: Automatically adjusts font size to fit container width
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- 🏷️ **Customizable Labels**: Add title, X-axis, and vertical Y-axis labels
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- 🎯 **Scrolling Data**: Old data automatically scrolls off as new data arrives
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- 🎨 **Terminal Theme**: Retro green-on-black aesthetic
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## Demo
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```
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Real-Time Data Visualization
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C 20 | X X X X X X X X X X X X X X X X X X X X
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o 19 | X X X X X X X X X X X X X X X X X X X X
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u 18 | X X X X X X X X X X X X X X X X X X X X
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n 17 | X X X X X X X X X X X X X X X X X X X X
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t 16 | X X X X X X X X X X X X X X X X X X X X
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15 | X X X X X X X X X X X X X X X X X X X X
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14 | X X X X X X X X X X X X X X X X X X X X
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13 | X X X X X X X X X X X X X X X X X X X X
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12 | X X X X X X X X X X X X X X X X X X X X
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11 | X X X X X X X X X X X X X X X X X X X X
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10 | X X X X X X X X X X X X X X X X X X X X
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9 | X X X X X X X X X X X X X X X X X X X X
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8 | X X X X X X X X X X X X X X X X X X X X
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7 | X X X X X X X X X X X X X X X X X X X X
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6 | X X X X X X X X X X X X X X X X X X X X
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5 | X X X X X X X X X X X X X X X X X X X X
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4 | X X X X X X X X X X X X X X X X X X X X
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3 | X X X X X X X X X X X X X X X X X X X X
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2 | X X X X X X X X X X X X X X X X X X X X
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1 | X X X X X X X X X X X X X X X X X X X X
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+----------------------------------------
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1 6 11 16 21 26 31 36 41
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Time (seconds)
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```
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## Installation
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Simply include the JavaScript file in your HTML:
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```html
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<script src="ascii-bar-chart.js"></script>
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```
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## Quick Start
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```html
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<!DOCTYPE html>
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<html>
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<head>
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<style>
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#chart {
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font-family: 'Courier New', monospace;
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background: #000;
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color: #0f0;
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padding: 20px;
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white-space: pre;
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}
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</style>
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</head>
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<body>
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<div id="chart"></div>
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<script src="ascii-bar-chart.js"></script>
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<script>
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// Create chart
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const chart = new ASCIIBarChart('chart', {
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maxHeight: 20,
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maxDataPoints: 30,
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title: 'My Chart',
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xAxisLabel: 'Time',
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yAxisLabel: 'Value'
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});
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// Add data
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chart.addValue(15);
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chart.addValue(23);
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chart.addValue(18);
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</script>
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</body>
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</html>
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```
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## API Reference
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### Constructor
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```javascript
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new ASCIIBarChart(containerId, options)
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```
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Creates a new ASCII bar chart instance.
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**Parameters:**
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| Parameter | Type | Required | Description |
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|-----------|------|----------|-------------|
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| `containerId` | string | Yes | ID of the HTML element to render the chart in |
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| `options` | object | No | Configuration options (see below) |
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**Options:**
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| Option | Type | Default | Description |
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|--------|------|---------|-------------|
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| `maxHeight` | number | `20` | Maximum height of the chart in rows |
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| `maxDataPoints` | number | `30` | Maximum number of columns before old data scrolls off |
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| `title` | string | `''` | Chart title (displayed centered at top) |
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| `xAxisLabel` | string | `''` | X-axis label (displayed centered at bottom) |
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| `yAxisLabel` | string | `''` | Y-axis label (displayed vertically on left side) |
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| `autoFitWidth` | boolean | `true` | Automatically adjust font size to fit container width |
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**Example:**
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```javascript
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const chart = new ASCIIBarChart('my-chart', {
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maxHeight: 25,
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maxDataPoints: 50,
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title: 'Server Response Times',
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xAxisLabel: 'Request Number',
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yAxisLabel: 'Milliseconds',
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autoFitWidth: true
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});
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```
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### Methods
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#### `addValue(value)`
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Adds a new data point to the chart.
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**Parameters:**
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- `value` (number): The numeric value to add to the chart
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**Example:**
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```javascript
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chart.addValue(42);
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chart.addValue(38);
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chart.addValue(45);
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```
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#### `clear()`
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Clears all data from the chart and resets it to initial state.
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**Example:**
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```javascript
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chart.clear();
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```
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## Features in Detail
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### Auto-Scaling Y-Axis
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The Y-axis automatically scales to show the full range of your data:
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- Minimum value always displays as one 'X' at the bottom
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- Maximum value uses the full chart height
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- Y-axis labels show actual data values, not just row numbers
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- Dynamically adjusts as new data arrives
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### Scrolling Data Window
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When the number of data points exceeds `maxDataPoints`:
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- Old data automatically scrolls off the left side
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- X-axis labels update to show actual data point numbers
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- Maintains a sliding window of the most recent data
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### Responsive Font Sizing
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When `autoFitWidth` is enabled:
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- Font size automatically adjusts to fill container width
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- Responds to window resizing in real-time
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- Maintains readability with min/max font size bounds (4px-20px)
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- Uses ResizeObserver for efficient updates
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### Vertical Y-Axis Label
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The Y-axis label is rendered vertically, one character per row:
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```
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V
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a
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l
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u
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e
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```
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## Advanced Usage
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### Real-Time Data Streaming
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```javascript
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const chart = new ASCIIBarChart('chart', {
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maxHeight: 20,
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maxDataPoints: 60,
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title: 'Live Metrics'
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});
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// Simulate real-time data
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setInterval(() => {
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const value = Math.random() * 100;
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chart.addValue(value);
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}, 1000);
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```
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### Integration with Data Sources
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```javascript
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// WebSocket example
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const ws = new WebSocket('ws://your-server.com/data');
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ws.onmessage = (event) => {
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const data = JSON.parse(event.data);
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chart.addValue(data.value);
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};
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// API polling example
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async function fetchAndUpdate() {
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const response = await fetch('/api/metrics');
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const data = await response.json();
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chart.addValue(data.currentValue);
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}
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setInterval(fetchAndUpdate, 5000);
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```
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### Multiple Charts
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```javascript
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const cpuChart = new ASCIIBarChart('cpu-chart', {
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title: 'CPU Usage %',
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yAxisLabel: 'Percent'
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});
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const memChart = new ASCIIBarChart('mem-chart', {
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title: 'Memory Usage MB',
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yAxisLabel: 'Megabytes'
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});
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// Update both charts
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cpuChart.addValue(45);
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memChart.addValue(2048);
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```
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## Styling
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The chart uses monospaced fonts and renders as plain text. Style the container element:
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```css
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#chart-container {
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font-family: 'Courier New', Courier, monospace;
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background-color: #000;
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color: #0f0;
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padding: 20px;
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border: 2px solid #0f0;
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border-radius: 5px;
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white-space: pre;
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overflow-x: auto;
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font-size: 12px;
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line-height: 1.0;
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}
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```
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## Browser Support
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- Modern browsers with ES6 support
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- ResizeObserver API (for auto-fit width feature)
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- All major browsers: Chrome, Firefox, Safari, Edge
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## License
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MIT License - feel free to use in your projects!
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## Examples
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See [`ascii-bar-chart.html`](ascii-bar-chart.html) for a complete working example with:
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- Interactive controls (Start/Stop/Reset)
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- Configurable settings (update interval, max columns, chart height)
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- Test data generator with increasing trend
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- Full styling and layout
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## Contributing
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Contributions welcome! This is a simple, focused library for ASCII-based charting.
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## Changelog
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### v1.0.0
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- Initial release
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- Dynamic vertical bar charts
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- Auto-scaling Y-axis
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- Scrolling data window
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- Responsive font sizing
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- Customizable labels and titles |