Accessing an object by index in an array of object in react native

Question

i have a basic array of object coming from an api something like:

[
{date:'2020-10-02, number: 400}, 
{date:'2020-10-01, number: 200},
... ]

And so on, actually i don't know how many items are in the array, but i need to get the last two

i corerctly download and store the data

my

console.log(data.lenght);

Shows the correct lenght of array (222 at the moment of writing);

As i said i need to show the latest date, the actual number and the difference with previous date; if i manually set the numbers it works as expected:

 <Text>
        {data[222].date} - {data[222].number}
        Variation {data[222].number - data[221].number}
 </Text>

but if i try to use the length of data as the index it give me an error: undefined is not an object (evaluating 'data[len].date'

len=data.length
...
 <Text>
    {len}
    {data[len].date} - {data[len].number}
    Variation {data[len].number - data[len-1].number}
 </Text>

len is printed correctly, i also tried to place it in {} double {{}} and other things like that i was wondering how can i access object using a "calculated" index

Nikhil bhatia · Accepted Answer · 2020-10-03 21:40:04Z

1

data.length will show total items, but array starts from 0,

{data[len - 1].date} - {data[len - 2].number}

should solve

answered Oct 3, 2020 at 21:40

Nikhil bhatia

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