js filter array of objects code example

Example 1: how to filter object in javascript

// use filter() function. Let say we have array of object.
let arr = [
  {name: "John", age: 30},
  {name: "Grin", age: 10},
  {name: "Marie", age: 50},
];
//Now I want an array in which person having age more than 40 is not
//there, i.e, I want to filter it out using age property. So
let newArr = arr.filter((person)=>(return person.age <= 40));
//filter function expects a function if it return true then it added 
//into new array, otherwise it is ignored. So new Array would be
/* [
	{name: "John", age: 30},
  	{name: "Grin", age: 10},
   ]
*/

Example 2: how to filter an array of objects in javascript

let arr=[{id:1,title:'A', status:true}, {id:3,title:'B',status:true}, {id:2, title:'xys', status:true}];
//find where title=B
let x = arr.filter((a)=>{if(a.title=='B'){return a}});
console.log(x)//[{id:3,title:'B',status:true}]

Example 3: js filter array of objects by value

var heroes = [
	{name: “Batman”, franchise: “DC”},
	{name: “Ironman”, franchise: “Marvel”},
	{name: “Thor”, franchise: “Marvel”},
	{name: “Superman”, franchise: “DC”}
];

var marvelHeroes =  heroes.filter(function(hero) {
	return hero.franchise == “Marvel”;
});

// [ {name: “Ironman”, franchise: “Marvel”}, {name: “Thor”, franchise: “Marvel”} ]

Example 4: filtering json array in javascript

const data = [
  {
    name: 'Bob',
    gender: 'male',
    age: 34,
  },
  {
    name: 'Carol',
    gender: 'female',
    age: 36,
  },
  {
    name: 'Ted',
    gender: 'male',
    age: 38,
  },
  {
    name: 'Alice',
    gender: 'female',
    age: 40,
  },
];

const arr1 = data.filter(d => d.age > 37);
console.log('arr1', arr1);

const arr2 = data.filter(d => d.gender === 'female');
console.log('arr2', arr2);

const ageAndGender = d => d.age > 37 && d.gender === 'female';

const arr3 = data.filter(ageAndGender);
console.log('arr3', arr3);

Example 5: javascript filter array of objects by key

var data = { records : [{ "empid": 1, "fname": "X", "lname": "Y" }, { "empid": 2, "fname": "A", "lname": "Y" }, { "empid": 3, "fname": "B", "lname": "Y" }, { "empid": 4, "fname": "C", "lname": "Y" }, { "empid": 5, "fname": "C", "lname": "Y" }] }
var empIds = [1,4,5]
var filteredArray = data.records.filter(function(itm){
  return empIds.indexOf(itm.empid) > -1;
});

filteredArray = { records : filteredArray };

Example 6: filter array object by its elements

const things = {
  thing: [
    { place: 'here', name: 'stuff' },
    { place: 'there', name: 'morestuff1' },
    { place: 'there', name: 'morestuff2' }, 
  ],
};

const removeDuplicates = (array, key) => {
  return array.reduce((arr, item) => {
    const removed = arr.filter(i => i[key] !== item[key]);
    return [...removed, item];
  }, []);
};

console.log(removeDuplicates(things.thing, 'place'));
// > [{ place: 'here', name: 'stuff' }, { place: 'there', name: 'morestuff2' }]