Let's say we have array of objects:

const data = [
  {
    firstName: "Bruce",
    lastName: "Wayne",
    address: "Arkham 6",
    id: "1",
  },
  {
    firstName: "Peter",
    lastName: "Parker",
     address: "LA 54",
    id: "2"
  },
  {
    firstName: "Tony",
    lastName: "Stark",
    address: null,
    id: "3"
  }
];

and want to get length of the array but exclude counting of the objects which has null values (in example above, this is the last object with address property null) so that result of the counting of the example above would be 2.

objectsWithoutNull = data.reduce(function (r, a) {
    return r + +( a!== null);
}, 0);

I'm trying with reduce method, but got 0. Where is the problem in iteration?

Let's say we have array of objects:

const data = [
  {
    firstName: "Bruce",
    lastName: "Wayne",
    address: "Arkham 6",
    id: "1",
  },
  {
    firstName: "Peter",
    lastName: "Parker",
     address: "LA 54",
    id: "2"
  },
  {
    firstName: "Tony",
    lastName: "Stark",
    address: null,
    id: "3"
  }
];

and want to get length of the array but exclude counting of the objects which has null values (in example above, this is the last object with address property null) so that result of the counting of the example above would be 2.

objectsWithoutNull = data.reduce(function (r, a) {
    return r + +( a!== null);
}, 0);

I'm trying with reduce method, but got 0. Where is the problem in iteration?

• javascript
• arrays
• javascript-objects

• 2 do you want to look at a specific property or at all properties? – Nina Scholz Commented May 22, 2019 at 10:48
• change to a.address!== null – Ravikumar Rajendran Commented May 22, 2019 at 10:52

6 Answers 6

You can filter() the array and than get object values and check where not includes null.

const data = [
  {
    firstName: "Bruce",
    lastName: "Wayne",
    address: "Arkham 6",
    id: "1",
  },
  {
    firstName: "Peter",
    lastName: "Parker",
     address: "LA 54",
    id: "2"
  },
  {
    firstName: "Tony",
    lastName: "Stark",
    address: null,
    id: "3"
  }
];

const notNullable = data.filter(obj=>!Object.values(obj).includes(null));
console.log(notNullable)
console.log(notNullable.length)

More about Object Values Filter Includes

Reduce the array, for each object get the values with Object.values(), and check with Array.includes() if it contains a null value. Negate with ! the boolean result of inclues, and use the + operator to convert to number. Add the number to the accumulator.

const data = [{"firstName":"Bruce","lastName":"Wayne","address":"Arkham 6","id":"1"},{"firstName":"Peter","lastName":"Parker","address":"LA 54","id":"2"},{"firstName":"Tony","lastName":"Stark","address":null,"id":"3"}];

const result = data.reduce((r, o) => 
  r + +!Object.values(o).includes(null)
, 0);

console.log(result);

An option is to iterate over the object-values of a and test if the value is equal to null. If we found a null don't increase our counter.

const data = [
  {
    firstName: "Bruce",
    lastName: "Wayne",
    address: "Arkham 6",
    id: "1",
  },
  {
    firstName: "Peter",
    lastName: "Parker",
     address: "LA 54",
    id: "2"
  },
  {
    firstName: "Tony",
    lastName: "Stark",
    address: null,
    id: "3"
  }
];

let objectsWithoutNull = data.reduce(function (r, a) {
  let hasNull = false;
  const values = Object.values(a);
  values.map(v => {
    if (v === null) {
      hasNull = true;
    }
  });
  
  return r + !hasNull;
}, 0);

console.log(objectsWithoutNull);

  objectsWithoutNull = data.reduce(function (r, a) {
        return r + +( Object.values(a).indexOf(null) == -1);
    }, 0); 

This will work if you want to check for all the properties!

You can use Array.prototype.every to check that all the values are not null

var length = data.filter(i => Object.values(i).every(i => i !== null)).length

If you are using lodash.

const data = [
      {
        firstName: "Bruce",
        lastName: "Wayne",
        address: "Arkham 6",
        id: "1",
      },
      {
        firstName: "Peter",
        lastName: "Parker",
         address: "LA 54",
        id: "2"
      },
      {
        firstName: "Tony",
        lastName: "Stark",
        address: null,
        id: "3"
      }
    ];

const counter = _.filter(data, ({address}) => {return address != null}).length;
console.log(counter);