Javascript how to calculate values inside array?

Question

I have this array :

arr = ["003448", "003609", "003729", "003800", "004178", "004362", "004410"];

I want to convert it become like this :

new_arr =  [161, 120, 71, 378, 184, 48];

161 result from 003609 - 003448

120 result from 003729 - 003609

and so on..

The rule is "The next value will be reduced by previous value". I have no clue with this. Anyone please help me.. I will be highly appreciate.

yes.. if we have array like this [1, 5, 9, 12] then by following the rule it will become 5-1 = 4, 9-5 = 4, 12-9 = 3 then the new array is [4, 4, 3] — fandiahm
– fandiahm, Commented Mar 28, 2017 at 2:00

rgthree · Accepted Answer · 2017-03-28 02:04:12Z

1

Your question seems to scream Array.reduce:

var arr = ["003448", "003609", "003729", "003800", "004178", "004362", "004410"];
var new_array = arr.reduce(function(a, currentValue, currentIndex, array) {
  var previousValue = array[currentIndex - 1];
  if (previousValue !== undefined)
    a.push(parseInt(currentValue, 10) - parseInt(previousValue, 10));
  return a;
 }, []);

 console.log(new_array);

answered Mar 28, 2017 at 2:04

rgthree

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1 Comment

nnnnnn Over a year ago

Note that the parseInt() calls are redundant, because the - operator coerces its arguments to be numbers.

Ngoan Tran · Accepted Answer · 2017-03-28 01:58:36Z

0

Try with below solution:

var arr = ["003448", "003609", "003729", "003800", "004178", "004362", "004410"];
var new_arr =  [];

for (var i=1; i<arr.length; i++){
  new_arr.push(arr[i]-arr[i-1]);
}

console.log(new_arr);

answered Mar 28, 2017 at 1:58

Ngoan Tran

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1 Comment

fandiahm Over a year ago

Thank you very much.. This is great!

diavolic · Accepted Answer · 2017-03-28 01:59:02Z

0

for (i=0; i<arr.length-1; i++)
   new_arr[] = parseInt(arr[i+1])-parseInt(arr[i])

answered Mar 28, 2017 at 1:59

diavolic

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