How to get color value from gradient by percentage with javascript?

Question

I have a fixed width div with gradient applied using css. I want to build slider based color picker based on this gradient.

When i drag the slider i calculate the pe

Answer 1

There is a nice lib that handles variety of color manipulations chroma.js

yarn add chroma-js

And then

import chroma from 'chroma-js';

const f = chroma.scale(['yellow', 'red', 'black']);

console.log( f(0.25).toString() );                    // #ff8000
console.log( f(0.5).css('rgba') );                    // rgba(255,0,0,1)
console.log( f(0.75).css() );                         // rgb(128,0,0)
console.log( f(1).css() );                            // rgb(0,0,0)