why my let variable does not changing or filtering?-CodePudding

I want to filter my products by id (remove one).

if I console log it works all right, but the variable does not change, the arr is the same. Why ?

const express = require('express');

const bodyParser = require('body-parser');

const app = express();

const path = require('path');

app.use(express.json());
app.use(express.urlencoded());

const js = require('./translation.json');

 app.use('/public', express.static('public'));

let mockProducts = [
  {
    id: '12',
    name: 'Gucci Bag3212',
    desc: 'Lorem ipsum dolor sit amet.',
    photos: [
      {
        image_id: '15',
        photo: 'https://picsum.photos/590/590'
      },
    ],
    price: 19.99,
  },
  {
    id: '13',
    name: 'Leather Shoes',
    desc: 'Lorem ipsum dolor sit amet',
    photos: [
      {
        image_id: '16',
        photo: 'https://picsum.photos/590/590'
      },
    ],
    price: 19.99,
  }
];

app.put('/remove_product/:id', (req, res) => {
 mockProducts.filter(el => el.id !== req.params.id);
 res.json({});
});

app.listen(4000, () => {
  console.log('LISTEN')
});

if I make console log this I get the right product:

id = 12
console.log(mockProducts.filter(el => el.id === req.params.id)) = 
  {
    id: '12',
    name: 'Gucci Bag3212',
    desc: 'Lorem ipsum dolor sit amet.',
    photos: [
      {
        image_id: '15',
        photo: 'https://picsum.photos/590/590'
      },
    ],
    price: 19.99,
  },

I am very thankful for your help I dont understand why its not working the arr does not change

CodePudding user response：

mockProducts.filter(el => el.id !== req.params.id);

This does not modify mockProducts but returns a new array. You need to send that back (or assign it to a variable in your function and act on it.)

CodePudding user response：

Because filter creates a copy of array, so original keeps the same, but you can reassign

mockProducts =  mockProducts.filter(el => el.id !== req.params.id);

this get return of filter, and modify original array