Calculate Tsinghua University GPA at the "All Scores", i.e. "本科生已修课程成绩查询" page

Tsinghua-GPA-calc.js

var reverse = (arr)=>{ // Array.prototype.reverse is overridden in a bloody way in the webpage
  const res = []
  for (let index = arr.length-1; index >= 0; index--) {
    const element = arr[index];
    res.push(element)
  }
  return res
}

(() => {
  var nameIx = 2
  var creditIx = 3
  var gpIx = 6
  var attrIx = 8
  var sideIx = 9
  var termIx = 10

  var courses = Array.from(
    document.querySelector("body > table:nth-child(44) > tbody").children
  )
    .slice(1, -1)
    .map((course) => {
      var c = course.children
      var gpRaw = c[gpIx].innerText
      return {
        name: c[nameIx].innerText,
        credit: Number(c[creditIx].innerText),
        gp: (gpRaw && gpRaw !== "N/A") ? Number(gpRaw) : undefined,
        attr: c[attrIx].innerText,
        side: c[sideIx].innerText === "辅修专业课程",
        term: c[termIx].innerText
      }
    })
    .filter(course => course.gp)

  var rr = courses.filter(course => course.attr === "必修" || course.attr === "限选")
  var major = courses.filter(course => !course.side)
  var side = courses.filter(course => course.side)

  var terms = {}
  courses.forEach((course) => {
    if (course.term.endsWith("-3")) {
      return
    }

    if (terms[course.term] === undefined) {
      terms[course.term] = [course]
    } else {
      terms[course.term].push(course)
    }
  })

  var years = {}
  reverse(courses).forEach((course)=>{
    const course_year = course.term.slice(0,4)

    if(years[course_year] === undefined){
      years[course_year] = []
    }

    for (const year of Object.values(years)) {
      year.push(course)
    }
  })

  var calc =
    (courses) =>
      courses
        .map(course => course.gp * course.credit)
        .reduce((x, y) => x + y) /
      courses
        .map(course => course.credit)
        .reduce((x, y) => x + y)

  console.log(
    `
------------ 整体情况 -----------

必限：${calc(rr)}
主修：${calc(major)}
辅修：${calc(side)}
所有：${calc(courses)}

---- 各春/秋学期, Single Term ----

${
    Object.keys(terms)
      .map((key) => {
        return {
          term: key,
          gp: calc(terms[key])
        }
      })
      .map(obj => obj.term + ": " + String(obj.gp))
      .join("\n")
    }

----- 各学年, Accumulated ------

${
  Object.keys(years)
    .map((key) =>({
      year: key,
      gp: calc(years[key])
    }))
    .map(obj => obj.year + ": " + String(obj.gp))
    .join("\n")
}
    `
  )
})();