CODEWITHSUNDEEP
javascript
ganesh kaspate
ganesh kaspate

Reputation: 2685

Get only property value of an element using map function

I was trying to get the property value only using a map function. I know If I use map then its going to return an array of elements. So, here is what I am trying to do.

I have this array, of object

mainarray = [{ foo : '1' , id:'2' }, { foo : '2' , id:'3' },{ foo : '1' , id:'4' }];

Now, here what I am doing is (data is some different array).

let count;
if (data) {
    if ((data[0].foo) && (data[0].foo)) {
        count = this.state.mainarray.map((object, index) => {
            if ((object.Id === data[0].id) && (data[0].foo === object.foo)) {
                return object;
            }
        });
    }
}

I have done like this. Now here, if it did not match anything then it returns an array with all undefined values, as many elements are there in that.

[undefined,undefined]

But I actually tried with object.foo, so it should return only that value, But it is not returning. So, I'am stuck over here. Can any one help me with this?

Upvotes: 1

Views: 2212

Answers (2)

ponury-kostek
ponury-kostek

Reputation: 8060

I think you want to use filter method

let count;
if (data) {
    if ((data[0].foo) && (data[0].foo)) {
        count = this.state.mainarray.filter((object) => (object.Id === data[0].id) && (data[0].foo === object.foo)).length;
    }
}

Upvotes: 1

Tholle
Tholle

Reputation: 112827

You might want to use find instead, and if a match was found you can use that object's foo value.

Example

const mainarray = [
  { foo: "1", id: "2" },
  { foo: "2", id: "3" },
  { foo: "1", id: "4" }
];
const idToFind = "3";

const obj = mainarray.find(element => element.id === idToFind);
const count = (obj && obj.foo) || "0";

console.log(count);

Upvotes: 0

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