NodeJS Can’t Access Variable Inside Callback

I believe this is a problem with it being async, but I do not know the solution.

    PagesController.buy = function() {

  var table="";
  Selling.find({}, function(err, res) {
    for (var i in res) {
      console.log(res[i].addr);
      table = table + "res[i].addr";
    }
  });
  this.table = table;
  console.log(table);
  this.render();
}

My issue is that this.table=table is returning undefined if I try access it outside of the function, and I cannot figure out how to display the table on the page.

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

The problem is the Selling.find is asynchronous and likely isn’t complete by the time the this.table = table is executed. Try something like the following.

PagesController.buy = function() {
  var that = this;
  Selling.find({}, function(err, res) {
    var table = '';
    for (var i in res) {
      console.log(res[i].addr);
      table = table + res[i].addr;
    }

    that.table = table;
    console.log(table);
    that.render();
  });
}

That will guarantee that table isn’t used until after the results have been fetched and table has been populated.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0