web 抓取 function 返回“未定义”，但在我使用 console.log 时有效

Question

const cheerio = require("cheerio");
const request = require("request");


function GetPhysicalDmg(champname) {
        request("https://champion.gg/champion/" + champname, (error, response, html) => {
        let matchupData = {}
        if (!error && response.statusCode == 200)
        {
            var $ = cheerio.load(html);
            var row = $('.footer-attr');
            var divvoorscript = row.prev().prev().html();
            eval(divvoorscript);
            var physicaldmg = Number(matchupData.championData.dmgComposition.physicalDmg);
            var magicdmg = Number(matchupData.championData.dmgComposition.magicDmg);
            var truedmg = Number(matchupData.championData.dmgComposition.trueDmg);
            return physicaldmg;
        }
    }); 
}
console.log(GetPhysicalDmg("Nautilus"))

The following logs "undefined" in the console. Apparently this is because request is an async function, and I've tried to use callback but can't wrap my head around how it works.

function GetPhysicalDmg(champname) {
        request("https://champion.gg/champion/" + champname, (error, response, html) => {
        let matchupData = {}
        if (!error && response.statusCode == 200)
        {
            var $ = cheerio.load(html);
            var row = $('.footer-attr');
            var divvoorscript = row.prev().prev().html();
            eval(divvoorscript);
            var physicaldmg = Number(matchupData.championData.dmgComposition.physicalDmg);
            var magicdmg = Number(matchupData.championData.dmgComposition.magicDmg);
            var truedmg = Number(matchupData.championData.dmgComposition.trueDmg);
            console.log(physicaldmg);
        }
    }); 
}

this returns the value as it should.

Answer 1

Here's what I would do:

const axios = require('axios');
const cheerio = require('cheerio');

const getPhysicalDmg = async champname => {
  let request = await axios.get("https://champion.gg/champion/" + champname)
  let matchupData = {}
  var $ = cheerio.load(request.data);
  var row = $('.footer-attr');
  var divvoorscript = row.prev().prev().html();
  eval(divvoorscript);
  var physicaldmg = Number(matchupData.championData.dmgComposition.physicalDmg);
  var magicdmg = Number(matchupData.championData.dmgComposition.magicDmg);
  var truedmg = Number(matchupData.championData.dmgComposition.trueDmg);
  return physicaldmg;
}

;(async function(){
  console.log(await getPhysicalDmg("Nautilus"))
})()

Hopefully this way is less confusing, it is to me at least. Also that eval in the middle is a really bad idea in general.