I have a problem to prevent adding new object to array which has the same value of id like existing element of object in array. My array is like this:
var arr = [
{id:1, name:'Fabricio'},
{id:2, name:'Leontina'},
{id:3, name:'Rodrigo'}];
If I want to add object like this {id:2; name:'Evander'}, that couldn't be done because of id.
You can check if an id is in the array as:
if(!arr.some(el => el.id === 2))
arr.push({ id: 2, name: "Evander" });
But actually this is a good usecase for a Map:
const users = new Map([
[1, { name: "one" }],
[2, { name: "two" }]
]);
So you can easily check if an id is already there in constant time:
if(!users.has(2))
users.set(2, { name: "newtwo" });
const users = new Map( arr.map( o => [o.id, o] ) ). With thanks to @JonasW. for the reminder about map.You can use Array#find:
const arr = [
{id:1, name:'Fabricio'},
{id:2, name:'Leontina'},
{id:3, name:'Rodrigo'}
];
function push(array, item) {
if (!array.find(({id}) => id === item.id)) {
array.push(item);
}
}
push(arr, {id: 2, name: 'Evander'}); // won't be added
push(arr, {id: 10, name: 'Kyle'}); // will be added
You can make use of array.filter function in the following way:
let array = [
{ id: 1, name: 'Fabricio' },
{ id: 2, name: 'Leontina' },
{ id: 3, name: 'Rodrigo' }
]
function add (object) {
if (object) {
if (array.filter(x => x.id === object.id).length === 0) {
array.push(object)
}
}
}
add({ id: 2, name: 'Evander' }) // won't add
add({ id: 4, name: 'Evander' }) // will add
console.log(array)