[ECMA] HowTo use array.findIndex?

I’m trying to find the index of an array-item in a JSON parsed string.
I tried it with:

idx=arr.findIndex (item->item.feature===“heating.sensors.temperature.outside”);

and got:

2021-07-02 19:57:10.744 [ERROR] [internal.handler.ScriptActionHandler] - Script execution of rule with UID 'HeizungsDaten_Neu' failed: <eval>:40:26 Expected an operand but found >
                          ^ in <eval> at line number 40 at column number 26

The displayed help for FindIndex (findIndex( callback: fn( element:number, index:number, array:TypedArray) -> bool:thisArg?) ->number leaves me without a clue.

As a response to an API call requesting several datapoints I get a JSON formated return. This JSON is containing an array of those data-points, sadly the order of the array elements is not as requested and can change (as I had to notice).

Show the code that parsed the JSON and extracted the array.

Assuming you are using the built in JavaScript, I don’t think -> is an operator in ECMAScript 5.1 which is the version openHAB comes with. You need to find the approach that works for that older version.

var returnvalue = HTTP.sendHttpGetRequest(url, headers, 10*1000);
 returnvalue = JSON.parse(returnvalue);

Yes, I’m using the build in ECMA rules, the error points as well to the -> .

Thanks for the help.

Back into searching.

Try converting it to an explicit function declaration:

idx = arr.findIndex(function(item) { item.feature===“heating.sensors.temperature.outside” });

Thanks for all inputs!
@pacive : Sorry, but that didn’t help either.

My (personal) solution:
While digging into the findIndex stuff I found that all solutions with .findIndex or .indexOf etc. are using a for..next loop behind the scene anyhow. As I would be using such method (correct term?) on virtually all array members the code in my rule migth look good, however I would run such a loop for every member. By running a single for..next loop in the rule once and using a select case on every member in order to get the correct value I should be fine!
My code is working!