index.js

let _ = require('lodash');
let fs = require('fs');
let path = require('path');
let querystring = require('querystring');
let express = require('express');
let axios = require('axios');
let estroke = require('./src/estroke.js');
let app = express();

app.get('/strokeorder/:chars', async function (req, res) {
  const sizeRef = 10000;
  const charCacheFile = path.join(__dirname, '/client/cache/char_cache.json');
  const buildCache = false;

  let ret = new Array(req.params.chars.length);
  let charCache = fs.existsSync(charCacheFile) ? JSON.parse(fs.readFileSync(charCacheFile)) : [];

  await Promise.all(
    req.params.chars.split('').map(async (currChar, idx) => {
      //from https://stackoverflow.com/a/37576787
      let cachedChar = charCache.find(existingChar => existingChar.character == currChar);
      if (cachedChar != undefined) {
        ret[idx] = cachedChar;
        return;
      }

      let currRes = (
        await axios.post(
          'http://www.eon.com.hk/common/fcg/estroke.fcg?task=getPhrase',
          querystring.stringify({
            uni: currChar,
            screenWidth: sizeRef,
            bias: 'Simplified',
          }),
        )
      ).data.split('\n');

      let params = ['cvec', 'sorder', 'pinyins'].map(e => currRes.find(l => l.indexOf(`${e}[0]`) != -1).split('"')[1]);
      ret[idx] = {
        character: currChar,
        strokes: estroke.parseStroke(params[0], params[1], sizeRef),
        pinyins: params[2].split(' '),
      };

      if (buildCache) {
        charCache.push(ret[idx]);
        console.log(`Added ${currChar} to character cache.`);
      }
    }),
  );

  if (buildCache) fs.writeFileSync(charCacheFile, JSON.stringify(charCache));
  res.send(JSON.stringify(ret));
});

app.use(express.static('client'));

app.listen(1275, function () {
  console.log('chinese-learner listening on port 1275');
});