filter on object javascript 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: javascript object filter

function objectFilter = (obj, predicate) => 
    Object.keys(obj)
          .filter( key => predicate(obj[key]) )
          .reduce( (res, key) => (res[key] = obj[key], res), {} );

// Example use:
var scores = {
    John: 2, Sarah: 3, Janet: 1
};

var filtered = objectFilter(scores, num => num > 1); 
console.log(filtered);

Example 3: js filter object

/** filter object by key or value */

/** filter object function */
function filterObj( obj, predicate ) {
	var result = {}, key;

	for ( key in obj ) {
		if ( obj.hasOwnProperty( key ) && predicate( key, obj[ key ] ) ) {
			result[ key ] = obj[ key ];
		}
	}

	return result;
};

// example

// set object
var obj = {
	name : 'john',
	lastName : 'smith',
	age : 32
}

// filter out parameters using key and value
var filteredObj = filterObj( obj, function( key, value ) {
	return key !== 'age' && value !== 'smith'
});

// show result
console.log( filteredObj ); // { name: "john" }

Example 4: can filter be used on objects in javascript

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 5: filter in js

const filterThisArray = ["a","b","c","d","e"] 
console.log(filterThisArray) // Array(5) [ "a","b","c","d","e" ]

const filteredThatArray = filterThisArray.filter((item) => item!=="e")
console.log(filteredThatArray) // Array(4) [ "a","b","c","d" ]

Example 6: array.filter in javascript

//Eg 1 - If item is unchecked, remove it from array

const array = [2, 3, 4]

if (event.target.checked) {
      newValue.push(option);
    } else {
      newValue = newValue.filter(item => item.id != option.id);
    }

//If false, it will remove the element. 2 is not equal to 2.

//Eg 2 - To return an array with length > 6

const words = ['spray', 'limit', 'elite', 'exuberant', 'destruction', 'present'];
const result = words.filter(word => word.length > 6);