Sum values inside an array

Question

I'm trying to sum the values inside an array depending on which levels they are but with no success for the moment.

Datas I'm working with ( named as the variable totalByLevel ) :

What I want :

Having each total per level inside 1 array, for example : ['total of 3 + 4', 'total of 6 + 7', etc...]

What I tried :

I tried to create an empty array and push the values from 3 + 4 into the array, which is working but not as intented.

Only the last values is kept in the array and all others are erased, if you have a fix for it I would really appreciate any help! Thank you in advance.

component.ts

for (const levelKey in this.totalByLevel ) {
        if (this.totalByLevel .hasOwnProperty(levelKey)) {
          const key = this.labelName[levelKey];
          const value = this.totalByLevel [levelKey][Object.keys(this.totalByLevel [levelKey])[0]];
          const value2 = this.labelName[Object.keys(this.totalByLevel [levelKey])[0]];
          const value3 = this.totalByLevel [levelKey][Object.keys(this.totalByLevel [levelKey])[1]];
          const value4 = this.totalByLevel [levelKey][Object.keys(this.totalByLevel [levelKey])[2]];

          this.output_object[key] = value;
          this.output_object2[key] =  value2;
          const sum = [];
          if (value4 !== undefined || null) {
            sum.push((+value + +value3 + +value4).toFixed(2));
            console.log(sum, 'SUM 3');
            this.totalPerCat = sum;

          } else if (value4 === undefined || null) {
             sum.push((+value + +value3).toFixed(2));
             console.log(sum, 'SUM 2');
             this.totalPerCat = sum;

          } else if (value3 === undefined || null) {
            sum.push(value);
            console.log(sum, 'SUM 1');
            this.totalPerCat = sum;

          }
          console.log(this.totalPerCat);
/*          console.log(value3);
          console.log(value4);
          console.log(+value + +value3 + +value4, 'SUM');*/
        }
      }
    });

You should probably read about truthy and falsy values in JS: developer.mozilla.org/en-US/docs/Glossary/Truthy (Not answering the question but this could greatly improved your if...else management) — Zer0
– Zer0, Commented Sep 7, 2020 at 7:48
@Zer0 so if I understand right, what I was doing wrong there is that I was overwriting the value inside the array each time my else if was triggered, am I right ? — Zephyr
– Zephyr, Commented Sep 7, 2020 at 8:15
First this and your if/else conditions are just not well put, for example value4 !== undefined || null: I assume you meant value4 !== undefined || value4 !== null? The code you wrote would just convert the null to false (due to falsy values), making it useless and only checking for undefined. But you could even take it further: value4 !== undefined || null => if (value4) value4 === undefined || null => if (!value4)`. That's the magic of truthy/falsy in JS ;) — Zer0
– Zer0, Commented Sep 7, 2020 at 8:29
Thank you a lot for the very good explication. I will for sure keep that in mind! — Zephyr
– Zephyr, Commented Sep 7, 2020 at 8:32

Vincent · Accepted Answer · 2020-09-07 07:57:04Z

1

Here you go:

const data={
    2:{3:"3514.80", 4:"7259.32"},
    5:{6:"864941.86", 7:"1076976.54"},
    8:{"":"14145.69"},
    9:{10:"223835.02", 11:"60978.31", 12:"5554.92"}
}

const result = Object.values(data).map(items => Object.values(items).map(val => Number(val)).reduce((a,b) => a + b, 0))

console.log(result)

answered Sep 7, 2020 at 7:57

Vincent

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Comments

Barremian · Accepted Answer · 2020-09-07 08:01:05Z

1

You could use the funcitons Object.values() and Array reduce in combination. Try the following

var totalByLevel = {
  2: {
    3: '3514.80',
    4: '7259.32'
  },
  5: {
    6: '864941.86',
    7: '1076976.54'
  }
};

var sum = Object.values(totalByLevel).reduce((acc, curr) => {
  acc.push(String(Object.values(curr).reduce((a, c) => a + Number(c), 0)));
  return acc;
}, []);

console.log(sum);

edited Sep 7, 2020 at 8:01

answered Sep 7, 2020 at 7:55

Barremian

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3 Comments

Zephyr Over a year ago

I'm getting the following : error TS2339: Property 'push' does not exist on type 'unknown'.

Barremian Over a year ago

@Zephyr: Did you give the seed value [] at the end of the first reduce?

Zephyr Over a year ago

Oh right! My bad sorry I rushed into it and actually didn't, works as well now!

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