noCanvas();

  fbaco_id = "u4123456789";

​

  document.querySelector("#convert").addEventListener("click", function () {

    let number = getStudentNumberFromKibacoID(

      document.querySelector("#kibaco_id").value

    );

    console.log("Student Number:", number);

  });

}

​

function getStudentNumberFromKibacoID(id) {

  // 現在の年度下二桁を求める

  let year = new Date().getFullYear() - 2000;

​

  let y10 = parseInt(year.toString().slice(0, 1));

  let y1 = parseInt(year.toString().slice(1, 2));

  let ky1 = parseInt(id.slice(1, 2));

  let ky10 = 0;

  /**

  year: 10の段 y10, 1の段 y1

  kibaco year: 10の段 ky10, ky1

  */

​

  if (ky1 > y1) {

    ky10 = y10 - 1;

    if (y10 * 10 + y1 - (ky10 * 10 + ky1) > 8) {

      alert("在籍し得ないkibaco idです: " + id);

    }

  } else {

    ky10 = y10;

  }

  return ky10.toString() + id.slice(1);

}

function draw() {

  background(220);

}

​