Increment a global variable with a change node

General
1

Hello,

is it possible to replace a function node containing the following code, with a change node?

var metric = global.get('metric');
metric++;
global.set('metric', metric);
2

Yes that's possible'
Set Global metric
JSONata expression
$globalContext("metric") + 1

1 Like
3

Thanks! Works great!

4

Amazing!
Where in the docs would you find that precious little gem?

5

IT HELPS TO READ THE DOCUMENTATION:
https://nodered.org/docs/user-guide/context

6

Of course, I do read the docs and I use that valuable information mentioned there.
However, this JSONata magic

was new to me! I read and re-read that piece of documentation, but I cannot find that JSONata magic! (Or do I miss something? Or can I just not connect the dots?)

7

Also if you look at the Jsonata expression editor all $functions are listed there, with their parameters.

8

In case you did not realise, JSONata is just a tool that is included in node-red. If you want a full explanation you need to look in the JSONata documentation.

9

I agree, that a complete Jsonata re-documentation would be out of scope for Node-RED. IMHO I would like to see the example above, how Jsonata can interact with messages, or context inside the Cookbook (https://cookbook.nodered.org/). It would be a good starting point to allude users to this powerful built-in.

10

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