Iterate through objects with array of objects inside and get keys index nodejs

Question

I'm stuck with a problem. I have a object with a array of objects inside and I want to iterate through it and in each array I get I want specific positions.

So I want for the first element to get the [0], the second I want [0], the third I want [2] and the last element I want [0].

values ************** [ anonymous { medium: [ 0.28, 0.26, 0.13 ] },
4|wscontro |   anonymous { medium: [ 13.51, 0.04, 0.75 ] },
4|wscontro |   anonymous { medium: [ 1527.58, 262.98, 27.4, 59.49 ] },
4|wscontro |   anonymous { medium: [ 60305.25, 0 ] } ]
4|wscontro | values type of -------- object
4|wscontro | values ************** [{"medium":[0.28,0.26,0.13]},{"medium":[13.51,0.04,0.75]},{"medium":[1527.58,262.98,27.4,59.49]},{"medium":[60305.25,0]}]
4|wscontro | item ---->>>  anonymous { medium: [ 0.28, 0.26, 0.13 ] }
4|wscontro | item ---->>>  anonymous { medium: [ 13.51, 0.04, 0.75 ] }
4|wscontro | item ---->>>  anonymous { medium: [ 1527.58, 262.98, 27.4, 59.49 ] }
4|wscontro | item ---->>>  anonymous { medium: [ 60305.25, 0 ] }

And I want to get

0.28, 13.51, 27.4, 60305.25

I dont know how to get the index of the key with my forEach.

my code:

var allPromises=[];                 

                allPromises.push(Database.Alerts.getDeviceSystemByDeviceId("system.load", device.id));
                allPromises.push(Database.Alerts.getDeviceSystemByDeviceId("disk_space.sda3", device.id));
                allPromises.push(Database.Alerts.getDeviceSystemByDeviceId("system.ram", device.id)); 
                allPromises.push(Database.Alerts.getDeviceSystemByDeviceId("platform.temperatures", device.id));

                Promise.all(allPromises).then(function(values){
                    console.log("values **************", values);
                    console.log("values type of --------", typeof(values));

                    console.log("values **************", JSON.stringify(values));

                    values.forEach(function(item){
                        console.log("item ---->>> ", item);
                    });

The second parameter to a forEach is the index.. eg.. ["a","b","c"].forEach((a, ix) => { console.log(a, ix); }) would show a a 0, b 1, c 2 — Keith
– Keith, Commented Sep 4, 2017 at 11:43

Guillaume Georges · Accepted Answer · 2017-09-04 11:42:48Z

1

Add an index parameter to the function called inside your forEach :

values.forEach(function(item, index){
    console.log("item ---->>> ", item);
    console.log("index --->>> ", index);
});

answered Sep 4, 2017 at 11:42

Guillaume Georges

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jonahe · Accepted Answer · 2017-09-04 11:47:41Z

1

Array.prototype.forEach as well as Array.prototype.map can actually give you the index as a second parameter into the callback. As you want to get back several numbers (perhaps in an array) then .map suits your needs pretty well.

const relevantValues = values.map(function(item, index){
      if(index == 2) { return item.medium[2] }
      else { return item.medium.[0] }
 });

That would make relevantValues equal [0.28, 13.51, 27.4, 60305.25].

answered Sep 4, 2017 at 11:47

jonahe

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