color-alpha

const A = require('color-alpha'); console.log('red', A('red', .35)) console.log('#f00', A('#f00', .35)) console.log('#ff0000', A('#ff0000', .35)) console.log('rgb(255, 0, 0)', A('rgb(255, 0, 0)', .35)) console.log('rgba(255, 0, 0, 1)', A('rgba(255, 0, 0, 1)', .35))