node-sparkline

A lightweight and zero-dependencies pure Node.js sparkline generator.

Table of Contents

• Table of Contents
• Presentation
• Installation
• Technical information
  • Node.js
  • Debugging
  • Tests
    • Linting
    • Unit
• Usage
  • Library
    • Import node-sparkline
    • sparkline(options)
    • Examples
  • Environment variables
  • Errors
    • Object structure
    • Codes
  • Known issues
  • Code of Conduct
  • Contributing
  • Support
  • Security
  • License

Presentation

node-sparkline is a sparkline generator written in pure Node.js using ES6 and ES7 features with no dependency. It calculates points based on values to finally generate a polyline in a pure SVG (Scalable Vector Graphics) format. These values could be prices during the last 7 fays for an example.

The aim of this project is to provide a very simple, lightweight, zero-dependency, fast and fully-tested sparkline generator in SVG format and let user tune height, width, stroke color, stroke width and stroke opacity.

Installation

npm install node-sparkline

npm i -S node-sparkline

Technical information

Node.js

• Language: JavaScript ES6/ES7
• VM: Node.js >=10.0.0

Debugging

• Own debugger embedded that writes on process.stderr when the DEBUG environment variable is set. See Environment variables.

Tests

Linting

ESLint with Airbnb base rules. See Airbnb JavaScript Style Guide.

npm run lint

Unit

Mocha and Chai.

npm test

Usage

Library

Import node-sparkline

node-sparkline module exports one function named sparkline.

const sparkline = require('node-sparkline');

sparkline(options)

• options<Object>:

  • values* <Array> An array of values to draw the sparkline.
  • width <Number> The width in pixels to fix for the generated SVG. Default: 135
  • height <Number> The height in pixels to fix for the generated SVG. Default: 50
  • stroke <String> The stroke color. An hexadecimal value or one of these generic names. Default: #57bd0f
  • strokeWidth <Number> The stroke width in pixels. Min: 0 Default: 1.25
  • strokeOpacity <Number> The stroke opacity. Min: 0 Max: 1 Default: 1

• Returns: <String> The SVG tags of the generated SVG image

• Throws: <InputError>

Examples

You can find examples here: docs/examples

In these examples please prefer a well-known and tested asynchronous logger over the use of console module.

const sparkline = require('node-sparkline');
const values = require('./values'); // values is an array

try {
  const svg = sparkline({
    values,
    width: 135,
    height: 50,
    stroke: '#57bd0f',
    strokeWidth: 1.25,
    strokeOpacity: 1,
  });

  // svg is a string with SVG + polyline tags
  // ...
} catch (e) {
  console.error(e.toString());
}

Environment variables

• DEBUG: used to debug node-sparkline.

  Examples:

  • DEBUG=node-sparkline:* will debug all node-sparkline modules that could use the debugger.
  • DEBUG=-node-sparkline:* will disable debugging any node-sparkline modules that could use the debugger.
  • DEBUG=* will debug all node-sparkline modules that could use the debugger plus other modules used in your project if they use an equivalent debugger.

Errors

Object structure

Errors emitted by node-sparkline inherit the native Error prototype.

{
  name,
  code,
  message,
  stack,
  toString(),
}

Codes

Known issues

/

Code of Conduct

This project has a Code of Conduct. By interacting with this repository, organization, or community you agree to abide by its terms.

Contributing

Please take a moment to read our Contributing Guidelines if you haven't done so yet.

Support

Please see our Support page if you have any questions or for any help needed.

Security

For any security concerns or issues, please visit our Security Policy page.

License

MIT.