is there a way to filter array based on flag inside an array

Question

I am trying to do filter an array based on flag isSome: true. I want to filter when that flag is not present in that array

var value = [
      { "somevalues": {},
        "moreDetails": {
          "isSome": "true"
        }
      },
      { "somevalues": {},
        "moreDetails": {}
      },
      { "somevalues": {},
        "moreDetails": {}
      },
    ]
const valuewithisSome = value.filter(o => o.moreDetails &&  o.moreDetails.isSome);
const valuewithoutisSome = value.filter(o => o.moreDetails &&  !o.moreDetails.isSome);
console.log(valuewithisSome);
console.log(valuewithoutisSome);

valuewithisSome is working as expected and returning array with isSome: true.

valuewithoutisSome is not working as expected as i don't want to pass isSome false in morevalues array, is there a way to filter without even passing that flag?

How exactly is the "without" version not working? As written it should be fine. — Pointy
– Pointy, Commented Dec 24, 2018 at 14:05
"Run code snippet" shows that it actually works. This is probably not your real code. — Nikola Markovinović
– Nikola Markovinović, Commented Dec 24, 2018 at 14:09

Pointy · Accepted Answer · 2018-12-24 14:09:30Z

1

The "without" code you already have should work:

const valuewithoutisSome = value.filter(o => o.moreDetails &&  !o.moreDetails.isSome);

The expression o.moreDetails.isSome will evaluate to undefined if the "isSome" property is missing or explicitly false-y, so !o.moreDetails.isSome will be true in that case.

Now while that will work, if you want to explicitly test for the property being false only when it's actually present, you can do this:

const valuewithoutisSome = value.filter(o => 
  o.moreDetails &&
  (!("isSome" in o.moreDetails) || !o.moreDetails.isSome)
);

That will only return false (and filter out the array entry) when the "isSome" property is present. If it's not, or if it's present and true, then the entry will be in the filtered result.

answered Dec 24, 2018 at 14:09

Pointy

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5 Comments

sai Over a year ago

Thank you much, thats a great help, but I was getting null in the console for valuewithoutisSome. Is there a way we can use .some() in that filter()?

Pointy Over a year ago

Well .filter() will never return null; are you sure your test code is really the same as what you posted? The code exactly as written in your question does not show null for valuewithoutisSome.

sai Over a year ago

It was working in the codesnippet here, when I try to do the same thing in my visual studio code, I am seeing an empty array for valuewithoutisSome

Pointy Over a year ago

Look carefully at your actual code, in particular for differences. There could be something that looks harmless but that is in fact a critical change.

sai Over a year ago

Thanks,my mock data actually doesn't have moreDetails in other arrays except the first one. I think thats what is making a difference.

mstfyldz · Accepted Answer · 2018-12-24 14:15:22Z

1

Your isSome property type is string. Remove double quetos from true.

{ "somevalues": {}, "moreDetails": { "isSome": true } },

answered Dec 24, 2018 at 14:15

mstfyldz

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2 Comments

Pointy Over a year ago

This is a good suggestion, though the string "true" does work. However isSome: "false" would also be true (which is why it's a good suggestion) :)

sai Over a year ago

I wanted it as boolean, I dont have double quotes for true. I somehow wrongly inserted in this mockdata, my apologies.

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