Get NodeID from inside OnEditPrepare

Developing Nodes
1

I have a use-case where I need to get a Node's ID from inside OnEditPrepare in the Node's HTML frontend code.

I figured out a way to do it but it seems clunky and am wondering if there is something built-in I can access or is there a better way to do it.

My method was to create a small script to load into custom nodes:
/resources/MyCustomNode/GetNodeID.js

//
// Add this to any node where you want access to the NodeID
// from within the NodeRed HTML code like inside OnEditPrepare
//
// window.myNodeID
//

if (!window.myNodeID) {
    window.myNodeID = null;
    // Event listener for selection changes in the Node-RED workspace
    RED.events.on('view:selection-changed', function(event) {
        if (event.nodes && event.nodes.length > 0) {
            window.myNodeID = event.nodes[0].id;
        } else {
            window.myNodeID = null;
        }
    });
}

And then load and access it in my Custom Node as such...

<script src="/resources/MyCustomNode/GetNodeID.js"></script>
<script type="text/javascript">

    RED.nodes.registerType('MyCustomNode',{
        category: 'SomeCategory',
        color: '#FDD0A2',
        inputs:1,
        outputs:1,
        icon: 'font-awesome/fa-arrow-right',
        align: 'right',
        label: ()=> { return this.nodeLabel||'MyCustomNode' },
        oneditprepare: ()=>{ 
                console.log('My Node ID: ', window.myNodeID);
            }
        }
    });

I looked for a while but couldn't find anything.

2

Have you tried inspecting this.id in your oneditprepare function?

3

When I inspect "this" there is no parameter called "id".

        oneditprepare: ()=>{ console.log(this); }

Unless I'm doing something wrong, I don't see it.

4

what about now?

oneditprepare: function() {
   console.log(this.id);
}
5

It returns

undefined

I must be doing something wrong but not sure what.

6

Ok. I see now. Changed it function() and it works.

Thanks. Much easier.

7

Yup - do you want to know why - or do you already know why that is?

8

In short, arrow functions do not bind their own this, for node-red nodes, we need the "correct" this.

https://www.codementor.io/@dariogarciamoya/understanding-this-in-javascript-with-arrow-functions-gcpjwfyuc

9

Nope not sure exactly why... guessing it has to do with scoping.

Thanks for the explanation

10

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