Adding elements to a global array via a callback function in JavaScript: A step-by-step guide

I am currently working on querying and adding users to a global array from my database. My goal is to store the elements in this global array so that I can access it from any part of my application.

app.get("/admin/orders", (req, res) => {
  Quote.find({}, (err, quotes) => {
    var products = [];
    var users = [];
    quotes.forEach((quote) => {
      User.findOne({ email: quote.user }, (err, user) => {
        if (!err) {
          users.push(user);
        }
      });
    });
    res.render("orders", { quotes: quotes, users: users, products: products });
  });
});

Despite not receiving any errors from the database and successfully retrieving my users, when trying to log the array I am getting an empty result.

javascriptexpressmongoose

Answer №1

When faced with a similar issue in my express project, I came up with a clever solution that did the trick. By adding an index counter inside the loop, I was able to get everything working smoothly:

app.get("/admin/orders", (req, res) => {
  Quote.find({}, (err, quotes) => {
    var products = [];
    var users = [];
    quotes.forEach((quote, index) => {
      User.findOne({ email: quote.user }, (err, user) => {
        if (!err) {
          users.push(user);
        }
        if (index+1 == quotes.length)
        {
            return res.render("orders", { quotes: quotes, users: users, products: products });
        }
      });
    });
    
  });
});

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