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: javascript filter array of objects by array
var arr = [1,2,3,4],
brr = [2,4],
res = arr.filter(f => !brr.includes(f));
console.log(res);
Example 4: 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 5: javascript filter array of objects
function isBigEnough(value) {
return value >= 10
}
let filtered = [12, 5, 8, 130, 44].filter(isBigEnough)
// filtered is [12, 130, 44]
Example 6: js filter object of objects
// Our data
const fruits = {
apple: {
qty: 300,
color: "green",
name: "apple",
price: 2
},
banana: {
qty: 130,
color: "yellow",
name: "banana",
price: 3
},
orange: {
qty: 120,
color: "orange",
name: "orange",
price: 1.5
},
melon: {
qty: 70,
color: "yellow",
name: "melon",
price: 5
}
};
// Now let"s create a map function
const map = (obj, fun) =>
Object.entries(obj).reduce(
(prev, [key, value]) => ({
...prev,
[key]: fun(key, value)
}),
{}
);
// Finally let's map by color for example
const myFruits = map(fruits, (_, fruit) => fruit.color);
/*
{ apple: 'green',
banana: 'yellow',
orange: 'orange',
melon: 'yellow' }
/*