Node.js Exported Array isn't filled-CodePudding

i want to export an Array. The Array is in my

Fact.js

var facts = [];

exports.facts = facts;

function init() {
    loadFacts();
}

exports.init = init;

function loadFacts() {
    if (facts.length === 0) {
        facts = [];
        SelectAll(function (messages) {
            facts = messages;
            console.log("loadFacts: "   JSON.stringify(facts));
        });
    }
}

async function SelectAll(callback) {
    myJsonArray = [{ info: "a", source: "b" }, { info: "c", source: "d" }];
    test = JSON.parse(JSON.stringify(myJsonArray))
    console.log("SelectAll: "   JSON.stringify(test));
    return callback(test);
}

In my server.js I call the init-Function to load my facts.

server.js

const express = require('express');
const bodyParser = require('body-parser');
const cors = require('cors');

const Fact = require('./Fact');

const app = express();

app.use(cors());
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));


Fact.init();

console.log("Server.js: "   JSON.stringify(Fact.facts));

In the server.js the Array Fact.facts is empty after calling the Function init().

Does anybody knows why this happens?

Thanks in Advance

CodePudding user response：

That is because you exported the initial facts array (which was empty), and then reassigned new array [] to facts variable. Exported array-object is not affected with your code. So instead of reassignment you need to modify your exported array object.

Changes:

const facts = []; // const just to ensure the reference to array is not overwritten

function init() {
  loadFacts();
}

function loadFacts() {
  if (facts.length === 0) {
    SelectAll(function (messages) {
      facts.push(...messages); // push instead of reassignment
      console.log("loadFacts: "   JSON.stringify(facts));
    });
  }
}

async function SelectAll(callback) {
  const myJsonArray = [
    { info: "a", source: "b" },
    { info: "c", source: "d" }
  ];
  const test = JSON.parse(JSON.stringify(myJsonArray));
  console.log("SelectAll: "   JSON.stringify(test));
  return callback(test);
}

module.exports = {
  facts: facts,
  init: init
};

Output will be:

SelectAll: [{"info":"a","source":"b"},{"info":"c","source":"d"}]
loadFacts: [{"info":"a","source":"b"},{"info":"c","source":"d"}]
Server.js: [{"info":"a","source":"b"},{"info":"c","source":"d"}]