如何发现 id，并等待现有的 Promise? [英] How to discover the id, and await an existing Promise?

问题描述

最简单的解决方案可能是一些添加一些之后等待承诺模式，或重用...() 或方法 parse()，如下所示.

The simplest solution is perhaps some await after adding some promise pattern, or reusing...
I not see how to reuse the Promise, that I suppose it already exists, into the method csv-parse.readFileSync(), or the method parse(), illustrated below.

另一个解决方案是添加更多的承诺和一些async/await:整个 LOAD 块可以是一个函数......但我也没有看到等待的地方.

Another solution is to add more promises and some async/await: the whole LOAD block can be a function... But I also not see where put the awaits.

'use strict';
const fs     = require('fs')
const path   = require('path')

// CONFIGS:
const cf_cover_dataset = '../data/cover.csv'
var COVER = null;

// LOAD external configs:
var COVER_file = path.resolve(__dirname, cf_cover_dataset);
if (path.extname(cf_cover_dataset)=='.csv') {
  const parse  = require('csv-parse') // npm i csv-parse  (not parse"r")
  let raw = []
  parse(fs.readFileSync( COVER_file ), {
    trim: true,
    skip_empty_lines: true
  })
  .on('readable', function(){
    let record
    while (record = this.read()){
      raw.push(record)  ; console.log('.')}
  })
  .on('error', function(err){ console.error(err.message) })
  .on('end', function(){

     // I NEED TO WAY THE END HERE, HOW TO?

    COVER = f(raw);
    console.log("1. cover from CSV");
  });
} else {
  COVER = JSON.parse(COVER_file)  // ... and WAY here
  console.log("1. cover from JSON");
}

console.log("2. END!!");

结果是

   2. END!!
   1. cover from JSON

如何在step1之后得到step2?

How to get step2 after step1?

推荐答案

这更多是一种解决方法，而不是真正的解决方案，例如使用等待.
(请编辑这个答案，它是一个维基，你可以纠正我的假设，我的英语，或添加线索和链接)

This is more one workaround, not a real solution using e.g. await.
(please edit this answer, it is a Wiki, you can correct my asumptions, my English, or add clues and links)

似乎唯一的解决方案是丑陋天真的解决方案，将所有软件封装在一个main()函数中:

Seems that the only solution is the ugly naive solution, encapsulating all software in a main() function:

if (path.extname(cf_cover_dataset)=='.csv') {
  ...
  parse(fs.readFileSync( COVER_file ), {
    ...
  })
  .on('readable', function(){
    ...
  })
  .on('error', function(err){ ... })
  .on('end', function(){
    COVER = f(raw);
    console.log("1. cover from CSV");
    main();
  });
} else {
  COVER = JSON.parse(COVER_file)  // ... and WAY here
  console.log("1. cover from JSON");
  main();
}

function main() {  // step2, ugly but run in sequence 
   console.log("2. END!!");
}

<小时>

我真正需要的是承诺的非文档名称，以便于等待所有人.查看问题

---

What I really need is the non-documented name of the promises to be easy to await all. See the problem

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