parsePastObs.js

// https://www.weather.go.kr/w/obs-climate/land/past-obs/obs-by-day.do?stn=143
{
    const year = document.querySelector("[name=yy]").value;
    const month = Number(document.querySelector("[name=mm]").value);
    const startDay = 10;
    const endDay = 19;
    const d = new Date(year, month-1, 1);
    const offset = d.getDay();
    const p = x => {
        const o = {};
        for (const m of x.matchAll(/(평균|최고|최저)기온:(-?\d+\.\d+)(?=℃)/g)) {
            o[m[1]] = Number(m[2]);
        }
        return o;
    };
    `${year}\t${month}\t` + [...document.querySelectorAll(".table-cal tr:nth-child(2n)>td")].slice(offset).slice(startDay-1, endDay).filter(x => x.textContent.trim().length !== 0).map(x => p(x.outerText)).map((x, i) => `${x["평균"]}\t${x["최고"]}\t${x["최저"]}`).join("\t");
}