exercism-ts/resistor-color-duo/resistor-color-duo.ts

export function decodedValue(colors: string[]): number {
  if (colors.length < 2) {
    throw new Error("Unexpected number of colors");
  }
  // Ignore extra colors.
  colors = colors.slice(0, 2);

  const res = colorCode(colors[0])*10+colorCode(colors[1]);
  return res;
}

export const colorCode = (name: string): number => {
  const num = COLORS.indexOf(name.toLowerCase())
  if (num == -1) {
    throw new Error(`Invalid color name "${name}"`);
  }
  return num;
}

export const COLORS: string[] = [
  'black',
  'brown',
  'red',
  'orange',
  'yellow',
  'green',
  'blue',
  'violet',
  'grey',
  'white',
];