How to filter object inside an array?

Question

I want to check condition inside array with single object.

let arr = [
  {
    name: "john",
    description: {
      height: 5.5,
      weight: 54,
    },
  },
  {
    name: "mary",
    description: {
      height: 5.8,
      weight: 65,
    },
  },
  {
    name: "smith",
    description: {
      height: 6.1,
      weight: 85,
    },
  },
];

let obj = {
  height: 5.8,
  weight: 65,
};

i want to compare the obj within the array and if its match one, i want to get the name. for ex, obj is equal to marry. i want to print mary. This is what i have tried.

let result = arr.filter((item) => item.description === obj )
console.log(result.name);

If you want to find the one for mary, why not item.name === 'mary'? — Taplar
– Taplar, Commented May 25, 2020 at 19:57
Otherwise generalized object equality is only true if the objects are the exact same objects in memory. If they are not, item.description === obj will be false, even if the key value pairs of both objects match. — Taplar
– Taplar, Commented May 25, 2020 at 19:58
i know only the height and weight of the person. with that information i want to find the name. — Nijus
– Nijus, Commented May 25, 2020 at 19:58
item.description.height === obj.height && item.description.weight === obj.weight — Taplar
– Taplar, Commented May 25, 2020 at 19:59

Nina Scholz · Accepted Answer · 2020-05-25 20:00:50Z

2

You could build a filter with the entries of the object and iterate all entries and check the values. Then map the names.

let array = [{ name: "john", description: { height: 5.5, weight: 54 } }, { name: "mary", description: { height: 5.8, weight: 65 } }, { name: "smith", description: { height: 6.1, weight: 85 } }],
    object = { height: 5.8, weight: 65 },
    filters = Object.entries(object),
    result = array
        .filter(({ description }) => filters.every(([key, value]) => description[key] === value))
        .map(({ name }) => name);

console.log(result);

answered May 25, 2020 at 20:00

Nina Scholz

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Comments

Taplar · Accepted Answer · 2020-05-25 20:04:15Z

1

You have to compare the desired keys against each other, rather than comparing the objects, as object equality is based upon their memory addresses being the same.

let arr = [
  {
    name: "john",
    description: {
      height: 5.5,
      weight: 54
    }
  },
  {
    name: "mary",
    description: {
      height: 5.8,
      weight: 65
    }
  },
  {
    name: "smith",
    description: {
      height: 6.1,
      weight: 85
    }
  }
];

let obj = {
  height: 5.8,
  weight: 65
};

console.log(
  arr.filter(item => item.description.height === obj.height && item.description.weight === obj.weight)
);

answered May 25, 2020 at 20:04

Taplar

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Comments

D. Seah · Accepted Answer · 2020-05-25 20:09:36Z

1

you can narrow down the the property that you want to filter on like this

  let arr = [{
      name: "john",
      description: {
        height: 5.5,
        weight: 54
      }
    },
    {
      name: "mary",
      description: {
        height: 5.8,
        weight: 65
      }
    },
    {
      name: "smith",
      description: {
        height: 6.1,
        weight: 85
      }
    }
  ];

  let obj = {
    height: 5.8,
    weight: 65
  };

  const filtered = arr.filter(({ description }) => description.height === obj.height && description.weight === obj.weight);
  console.log(filtered)

answered May 25, 2020 at 20:09

D. Seah

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Comments

Rajneesh · Accepted Answer · 2020-05-26 07:31:25Z

1

One approach would be using Object.keys.

var arr = [ { name: "john", description: { height: 5.5, weight: 54, }, }, { name: "mary", description: { height: 5.8, weight: 65, }, }, { name: "smith", description: { height: 6.1, weight: 85, }}];

var obj = { height: 5.8, weight: 65 };

var result = arr.filter(({description})=>Object.keys(description).every(k=>description[k]==obj[k])).map(({name})=>name);

console.log(result);

answered May 26, 2020 at 7:31

Rajneesh

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Comments

Gopinath · Accepted Answer · 2020-05-25 20:18:59Z

The root cause for the failure of filter filter condition is due to the comparison between objects being attempted.

Comparison of objects can be done by using a helper function.

Here is the working exmaple:

// array-filter-demo.js
let arr = [
    { name: "john", description: { height: 5.5, weight: 54 } },
    { name: "mary", description: { height: 5.8, weight: 65 } },
    { name: "smith",description: { height: 6.1, weight: 85 } }
  ]

let obj = { height: 5.8, weight: 65 }

// Helper function to compare objects
function matching(a, b) {
   return ( a.height === b.height && a.weight === b.weight)
}

// Call the helper function inside filter
const result = arr.filter(item => (matching(item.description, obj)))
console.log(result)

Output:

$ node array-filter-demo.js 

[ { name: 'mary', description: { height: 5.8, weight: 65 } } ]

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