Get Horoscope Sign By DOB (Javascript)

get_horoscope_sign_by_dob.js

const SIGN_NAMES = [
  {
    sign: 'Aquarius',
    start: {
      day: 20,
      month: 1,
    },
    end: {
      day: 18,
      month: 2,
    }
  },
  {
    sign: 'Pisces',
    start: {
      day: 19,
      month: 2,
     },
    end: {
      day: 20,
      month: 3,
    }
  },
  {
    sign: 'Aries',
    start: {
      day: 21,
      month: 3,
    },
    end: {
      day: 19,
      month: 4,
    }
  },
  {
    sign: 'Taurus',
    start: {
      day: 20,
      month: 4,
    },
    end: {
      day: 20,
      month: 5,
    }
  },
  {
    sign: 'Gemini',
    start: {
      day: 21,
      month: 5,
    },
    end: {
      day: 20,
      month: 6,
    }
  },
  {
    sign: 'Cancer',
    start: {
      day: 21,
      month: 6,
    },
    end: {
      day: 22,
      month: 7,
    }
  },
  {
    sign: 'Leo',
    start: {
      day: 23,
      month: 7,
    },
    end: {
      day: 22,
      month: 8,
    }
  },
  {
    sign: 'Virgo',
    start: {
      day: 23,
      month: 8,
    },
    end: {
      day: 22,
      month: 9,
    }
  },
  {
    sign: 'Libra',
    start: {
      day: 23,
      month: 9,
    },
    end: {
      day: 22,
      month: 10,
    }
  },
  {
    sign: 'Scorpio',
    start: {
      day: 23,
      month: 10,
    },
    end: {
      day: 21,
      month: 11,
    }
  },
  {
    sign: 'Sagittarius',
    start: {
      day: 22,
      month: 11,
    },
    end: {
      day: 21,
      month: 12,
    }
  },
  {
    sign: 'Capricorn',
    start: {
      day: 22,
      month: 12,
    },
    end: {
      day: 19,
      month: 1,
    }
  },
];

function horoscopeSignName(dob) {
  if (dob && dob.month && dob.day) {
    const startLimitSign = getLimitSignByMonth(dob.month, true);
    const endLimitSign = getLimitSignByMonth(dob.month, false);
    if ((dob.month === startLimitSign.start.month && dob.day < startLimitSign.start.day) ||
        (dob.month === endLimitSign.start.month && dob.day < endLimitSign.start.day)) {
      return startLimitSign;
    }
    return endLimitSign;
  }
}

 function getLimitSignByMonth(month, isStart) {
  return SIGN_NAMES.find(sign => {
    return isStart ? sign.end.month === month : sign.start.month === month;
  });
}

// examples
console.log(horoscopeSignName({month:2, day:18})) //Aquarius
console.log(horoscopeSignName({month:3, day:21})) //Aries