dynamic color blending

colorCalc.js

//jshint esnext:true
// curveColors should have a length longer than or equal to 1
// the colors are split evenly- with a curveColors length of 3
// with said curveColors, a score of 75 would respond to halfway between index 1 and 2
const curveColors = [{r: 49, g: 198, b: 84},
                     {r: 46, g: 48, b: 193},
                     {r: 193, g: 138, b: 44},
                     {r: 193, g: 44, b: 44}]
// score should be between 0-100
const score = 50

const colorCalc = {
  calculateBetweenColors: function (btwnPos, startColorObj, endColorObj) {
    return ['r', 'g', 'b'].reduce((rgbObj, colorLet) => {
      const startCol = startColorObj[colorLet]
      const endCol = endColorObj[colorLet]
      rgbObj[colorLet] = Math.abs(startCol - endCol) * btwnPos + Math.min(startCol, endCol)
      return rgbObj
    }, {})
  },
  curveColorObj: function (thisScore) {
    const curveColorPosition = thisScore * ((curveColors.length - 1) / 100)
    const betweenPosition = curveColorPosition % 1
    return this.calculateBetweenColors(betweenPosition,
        curveColors[Math.floor(curveColorPosition)], curveColors[Math.ceil(curveColorPosition)])
  },
  curveColor: function (colorObj) {
    return `rgb(${colorObj.r}, ${colorObj.g}, ${colorObj.b})`
  }
}

let bgColor = colorCalc.curveColor(colorCalc.curveColorObj(score))
console.log(bgColor)
//document.body.style.backgroundColor = bgColor