Gradient Parser

About

Parse CSS gradient definitions and return an AST object.

Examples

  var gradient = require('gradient-parser');
  var obj = gradient.parse('linear-gradient(30deg, #000, transparent)');
  console.log(JSON.stringify(obj, null, 2));

Results in:

[
  {
    "type": "linear-gradient",
    "orientation": {
      "type": "angular",
      "value": "30",
      "unit": "deg"
    },
    "colorStops": [
      {
        "type": "hex",
        "value": "000"
      },
      {
        "type": "literal",
        "value": "transparent"
      }
    ]
  }
]

Installation

Install via npm:

npm install gradient-parser

Import in Node.js (CommonJS):

const gradient = require('gradient-parser');

Import in Node.js (ESM):

import { parse, stringify } from 'gradient-parser';

For browser usage:

<script src="node_modules/gradient-parser/build/web.js"></script>

Or download the zip

Development

Project Status

Gradient-parser has been modernized (as of v1.1.0):

• Removed Bower support in favor of npm exclusively
• Replaced Grunt with a modern build system using esbuild
• Added minification support
• Updated dependencies to specific versions
• Improved npm scripts for better developer experience

Build

Gradient-parser uses a modern build system with esbuild for building and minification.

# Build both Node.js and web bundles
npm run build

# Build only Node.js bundle
npm run build:node

# Build only web bundle
npm run build:web

# Build minified bundles
npm run build:minify

Testing

Run the test suite with:

npm test

The build step runs automatically before tests via the pretest script.

Starting a local server

You can run a simple HTTP server for development:

npm start

API

gradient.parse(gradientString)

Accepts a CSS gradient definition as declared in background-image and returns an AST as an Array of gradient nodes.

var ast = gradient.parse('linear-gradient(to right, red, blue)');

gradient.stringify(ast)

Accepts an AST (as returned by parse) and serializes it back into a CSS gradient string.

var css = gradient.stringify(ast);
// => 'linear-gradient(to right, red, blue)'

Round-trip is supported:

gradient.stringify(gradient.parse(input)) === input

AST

Common properties

All nodes have the following properties.

type

String. The possible values are the ones listed in the Types section below.

Types

The available values of node.type are listed below, as well as the available properties of each node (other than the common properties listed above).

linear-gradient

• orientation: Object or undefined. Possible types directional or angular.
• colorStops: Array of color stops.

repeating-linear-gradient

• orientation: Object or undefined. Possible types directional or angular.
• colorStops: Array of color stops.

radial-gradient

• orientation: Array or undefined. Array of possible types shape, default-radial, extent-keyword.
• colorStops: Array of color stops.

repeating-radial-gradient

• orientation: Array or undefined. Array of possible types shape, default-radial, extent-keyword.
• colorStops: Array of color stops.

conic-gradient

• orientation: Object or undefined of type conic.
• colorStops: Array of color stops.

repeating-conic-gradient

• orientation: Object or undefined of type conic.
• colorStops: Array of color stops.

Color Stops

Each color stop has the following properties:

• type: String one of literal, hex, rgb, rgba, hsl, hsla, var.
• value: the color value (type varies, see color types below).
• length: Object or undefined. Position of the color stop (see length types).
• length2: Object or undefined. Second position for dual-position color stops.

directional

• value: String possible values left, top, bottom, right, left top, left bottom, right top, right bottom, top left, top right, bottom left, bottom right.

angular

• value: String numeric value of the angle.
• unit: String one of deg, rad, grad, turn.

conic

• angle: Object or undefined of type angular.
• at: Object or undefined of type position.

literal

• value: String literal name of the color.

hex

• value: String hex value (3, 4, 6, or 8 digits, without # prefix).

rgb

• value: Array of length 3 of String numbers.

rgba

• value: Array of length 4 of String numbers.

hsl

• value: Array of length 3: [hue, saturation, lightness]. Hue is a String number, saturation and lightness are String numbers without the % suffix.

hsla

• value: Array of length 4: [hue, saturation, lightness, alpha]. Same as hsl with an additional alpha String number.

var

• value: String the CSS custom property name (e.g. --color-red).

calc

• type: 'calc'
• value: String the raw calc expression content (e.g. 50% + 25px).

shape

• style: Object or undefined possible types extent-keyword, px, em, rem, %, position, or position-keyword.
• value: String possible values ellipse or circle.
• at: Object or undefined of type position.

default-radial

• at: Object of type position.

position

• value: Object with x and y properties, each a length/keyword node.

position-keyword

• value: String possible values center, left, top, bottom, or right.

extent-keyword

• value: String possible values closest-side, closest-corner, farthest-side, farthest-corner, contain, or cover.

Length types

Length nodes can be any of: px, em, rem, vw, vh, vmin, vmax, ch, ex, %, calc.

• value: String numeric value (for calc, the expression string).

License

(The MIT License)

Copyright (c) 2014-2025 Rafael Caricio rafael@caricio.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.