Can't access element of Array

Question

I'm adding elements to an array using a service, which successfully adds the elements. I can see the data populated with a console.log

I can't however access the element.

this.routingService.getNode(startNode).subscribe(node => {
      node.forEach(node => {
        this.openSet.push(new MapNode(node.id, node.lon, node.lat, this.routingService.getNodeNeighbours(node.id)));
      });
    });

    console.log(this.openSet); // this prints out the below screenshot

However, when I use something like:

console.log(this.openSet[0]);

I get output of 'undefined'. I'm not sure if I'm being really thick right now in how I'm accessing it or not...

Any ideas?

can you post what you see when you do console.log(JSON.stringify(this.openSet)); — Sajeetharan, Nov 25 '17 at 16:31
Possible duplicate of [How to return the response from an asynchronous call?](https://stackoverflow.com/questions/14220321/how-to-return-the-response-from-an-asynchronous-call) — baao, Nov 25 '17 at 16:33
@baao how will this question be a duplicate of the one you mentioned. Can you elaborate? — Aravind, Nov 25 '17 at 16:36

score 1 · Accepted Answer · answered Nov 25 '17 at 16:39

1

subscribe works asynchron, so console.log() will log before the forEach loop runs. It's the same async behaviour as in this little piece of code

let foo = [];

setTimeout(() => {
  foo.push(1);
  foo.push(2);
}, 500);

console.log(foo); // logs []

Please see the duplicate post for options on how to work with asynchronity.

How to return the response from an asynchronous call?

answered Nov 25 '17 at 16:39

baao

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Ah, I see what you mean. printing out the array using JSON.stringify returned empty, so confirms your answer. Thank you! :) – Travisty Nov 25 '17 at 16:50

Can't access element of Array

1 Answers1