如何在chart.js中求和/除数组值？

Question

I have this variable to put in my chart:

var datiedu2 = {
            "labels": ['Lavori non terminati', 'Lavori in corso'],
            "datasets": 
                      [{
                           label: 'Numero',
                           data: [arrayItem['Value1'] + arrayItem['Value2']],
                           backgroundColor: 'rgb(255, 99, 132)',
                           borderWidth: 1
                      }]
               };

I can't get to make sum or division with array items. These belong to a variable whose structure is like:

 var myJSON = [
  {
    "": 0,
    "Comune": "BONDENO",
    "PUNTEGGIOSCUOLA1516": 4.25,
    "Value 1": 63,
    "Value 2": 8,
    "Value 3": 17,
    "DANNO": 6,
    "Somma valori": 88,
  },
  {
    "": 1,
    "Comune": "CAVEZZO",
    "PUNTEGGIOSCUOLA1516": 3.75,
    "Value 1": 23,
    "Value 2": 2,
    "Value 3": 9,
    "DANNO": 8,
    "Somma valori": 34,

  }

What is the best option to do it?

Thanks.

Answer 1

Just loop over the json array and then add the values to the sum variable and then add it to chart.

This code will do:

var sum=0;
for(item of myJSON)
{
    let subsum=item["Value 1"]+item["Value 2"]+item["Value 3"];
    sum+=subsum;
}

Then update the code like this:

var datiedu2 = {
            "labels": ['Lavori non terminati', 'Lavori in corso'],
            "datasets": 
                      [{
                           label: 'Numero',
                           data: sum,
                           backgroundColor: 'rgb(255, 99, 132)',
                           borderWidth: 1
                      }]
               };

Answer 2

Sums the properties Value 1 and Value 2

 var myJSON = [{ "": 0, "Comune": "BONDENO", "PUNTEGGIOSCUOLA1516": 4.25, "Value 1": 63, "Value 2": 8, "Value 3": 17, "DANNO": 6, "Somma valori": 88, }, { "": 1, "Comune": "CAVEZZO", "PUNTEGGIOSCUOLA1516": 3.75, "Value 1": 23, "Value 2": 2, "Value 3": 9, "DANNO": 8, "Somma valori": 34, } ]; function getSum(arr) { const sum = arr.reduce((acc, x) => acc + x['Value 1'] + x['Value 2'], 0); return sum; } const result = getSum(myJSON); console.log(result)