Saltcat Gradient Parser

About

Saltcat Gradient Parser is a fork of the original gradient-parser by Rafael Caricio, designed to support custom CSS easing extensions and enhanced CSS features.

Parse CSS3 gradient definitions and return AST object with extended support for:

• CSS variables (custom properties) in colors
• Enhanced calc() expressions
• Improved legacy gradient syntax parsing

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"
    },
    "colorStops": [
      {
        "type": "hex",
        "value": "000"
      },
      {
        "type": "literal",
        "value": "transparent"
      }
    ]
  }
]

Installation

Install via npm:

npm install saltcat-gradient-parser

Import in Node.js:

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

For browser usage:

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

Or download the zip

Fork Enhancements

This fork extends the original gradient-parser with the following custom CSS easing extensions:

CSS Easing Functions Support

Parse gradients with CSS easing functions for custom interpolation:

var gradient = require('saltcat-gradient-parser');
var obj = gradient.parse('linear-gradient(ease, red, blue)');
var obj2 = gradient.parse('linear-gradient(cubic-bezier(0.25, 0.1, 0.25, 1), to right, red, blue)');

Supported easing functions:

• linear
• ease
• ease-in
• ease-out
• ease-in-out
• cubic-bezier(x1, y1, x2, y2)

CSS Variables Support

var gradient = require('saltcat-gradient-parser');
var obj = gradient.parse('linear-gradient(45deg, var(--primary-color), #fff)');

Enhanced Calc() Expressions

var obj = gradient.parse('linear-gradient(to right, red calc(50% - 10px), blue)');

Improved Legacy Syntax

Better parsing of legacy gradient syntax including directional keywords without the to prefix:

var obj = gradient.parse('linear-gradient(bottom, #000, #fff)');

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

Starting a local server

You can run a simple HTTP server for development:

npm start

API

gradient.parse

Accepts the gradient definitions as it is declared in background-image and returns an AST object.

AST

Common properties

All nodes have the following properties.

type

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

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

• easing: Object or undefined. Easing function of type easing.
• orientation: Object possible types directional or angular.
• colorStops: Array of color stops of type literal, hex, rgb, or rgba.

repeating-linear-gradient

• easing: Object or undefined. Easing function of type easing.
• orientation: Object possible types directional or angular.
• colorStops: Array of color stops of type literal, hex, rgb, or rgba.

radial-gradient

• easing: Object or undefined. Easing function of type easing.
• orientation: Array or undefined. Array of possible types shape, default-radial.
• colorStops: Array of color stops of type literal, hex, rgb, or rgba.

repeating-radial-gradient

• easing: Object or undefined. Easing function of type easing.
• orientation: Array or undefined. Array of possible types shape, default-radial.
• colorStops: Array of color stops of type literal, hex, rgb, or rgba.

directional

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

angular

• value: Number integer number.

literal

• value: String literal name of the color.

hex

• value: String hex value.

rgb

• value: Array of length 3 of Number's.

rgba

• value: Array of length 4 or Number's.

shape

• style: Object or undefined possible types extent-keyword, px, em, %, or positioning-keyword.
• value: String possible values ellipse or circle.
• at: Object of attributes:
  • x: Object possible types extent-keyword, px, em, %, or positioning-keyword.
  • y: Object possible types extent-keyword, px, em, %, or positioning-keyword.

default-radial

• at: Object of attributes:
  • x: Object possible types extent-keyword, px, em, %, or positioning-keyword.
  • y: Object possible types extent-keyword, px, em, %, or positioning-keyword.

positioning-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.

easing

• value: String CSS easing function value (e.g., "ease", "cubic-bezier(0.25, 0.1, 0.25, 1)").

License

(The MIT License)

Copyright (c) 2014-2025 Rafael Caricio [email protected]
Saltcat extensions Copyright (c) 2025 Durable Programming Team

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.