JSON math on object array values

Question

I'm trying to multiply two components together in my object array

{
  "rx": {
    "vials": [
      {
        "description": "Rx 1",
        "strength": 100,
        "form": "ML",
        "pkg_size": 10,
        "case_size": 1,
        "total_units": strength * pkg_size,
        "ndc": "12345-1234-12",
        "covered": true
      }
    ]
  }
}

But if I do something like

$( "#demo" ).html( rx.vials[0].total_units );

I get nothing or NaN

What am I doing wrong??

Check the path again! This rx.insulin.vials[0].total_units will throw an error if called on the object you provided! — ibrahim mahrir
– ibrahim mahrir, Commented Apr 5, 2017 at 14:41
That was a typo. Even if I correct the path to $( "#demo" ).html( rx.vials[0].total_units ); I still don't get what I need. — sixtwowaifu
– sixtwowaifu, Commented Apr 5, 2017 at 15:13
Where do trength * pkg_size come from? If there is a problem it's in them! — ibrahim mahrir
– ibrahim mahrir, Commented Apr 5, 2017 at 15:16

Rohìt Jíndal · Accepted Answer · 2017-04-06 08:32:59Z

1

You can try something like this :

You can add total_units property into vials[0] after doing the calculation.

var jsonObj = {
  "rx": {
    "vials": [
      {
        "description": "Rx 1",
        "strength": 100,
        "form": "ML",
        "pkg_size": 10,
        "case_size": 1,
        "ndc": "12345-1234-12",
        "covered": true
      }
    ]
  }
};

jsonObj.rx.vials[0].total_units = jsonObj.rx.vials[0].strength * jsonObj.rx.vials[0].pkg_size;

console.log(jsonObj.rx.vials[0].total_units);

answered Apr 6, 2017 at 8:32

Rohìt Jíndal

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Comments

strah · Accepted Answer · 2017-04-05 15:10:35Z

1

You can not do that. If you want to do some math inside an object you have to use external variables - you can't access object's properties from within itself.

answered Apr 5, 2017 at 15:10

strah

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1 Comment

sixtwowaifu Over a year ago

So something like $( "#demo" ).html( rx.vials[0].strength * rx.vials[0].pkg_size ); ?

Emad Salah · Accepted Answer · 2017-04-06 12:47:42Z

1

You can try something like this:

for (var i = 0; i < rx.vials.length; i++) {
  rx.vials[i].total_units = rx.vials[i].strength * rx.vials[i].pkg_size;
}

console.log(rx.vials[0].total_units);

answered Apr 6, 2017 at 12:47

Emad Salah

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