Connect SQL Server and nodejs with docker-compose

I have the docker-compose.yml:

version: "3.7"
services:
  app:
    build: .
    ports:
      - 3000:3000
    working_dir: /app
    volumes:
      - ./:/app
    depends_on:
      - db
  db:
    image: "mcr.microsoft.com/mssql/server:2019-latest"
    ports:
      - 1433:1433
    environment:
      SA_PASSWORD: "Thieu@098551298"
      ACCEPT_EULA: "Y"
    volumes:
      - mssql-data:/var/opt/mssql
volumes:
  mssql-data:

file Dockerfile:

FROM node:12-alpine
ENV NODE_ENV=production

WORKDIR /app

COPY ["package.json", "package-lock.json*", "./"]

RUN npm install --production

COPY . .

CMD [ "node", "server.js" ]

file server.js:

var express = require("express");
var app = express();
var { ExecuteSQL } = require("./sql");

app.get("/", async (req, res) => {
    var s = await ExecuteSQL("select *from post");
    res.send(s.recordset);
});

app.listen(3000, () => console.log("listening on port 3000"));

And sql.js:

var sql = require("mssql");

var config = {
    user: "sa",
    password: "Thieu@098551298",
    server: "localhost",
    database: "blog",
    options: {
        enableArithAbort: true,
        trustServerCertificate: true,
    },
};

function ExecuteSQL(query) {
    return new Promise((resolve, reject) => {
        sql.connect(config, (err, db) => {
            if (err) reject(err);
            var request = new sql.Request();
            request.query(query, (err, db) => {
                if (err) reject(err);
                resolve(db);
            });
        });
    });
}
async function z() {
    var z = await ExecuteSQL("select *from post");
    console.log(z.recordsets);
}
z();
module.exports = {
    ExecuteSQL: ExecuteSQL,
};

Step 1: I run this cmd: docker-compose up -d (That will running two container db and app)

Step 2: I open browser go to http://localhost:3000/ (My goal is the browser will show the recordset when i select *from post from the server.js file) but it will throw err:

UnhandledPromiseRejectionWarning: ConnectionError: Failed to connect to localhost:1433 - Could not connect (sequence)

But when I run cmd: node sql - It can connect to SQL Server in the container and show data because I have the function for test in sql.js:

async function z() {
    var z = await ExecuteSQL("select *from post");
    console.log(z.recordsets);
}
z();

Data show:

[
  [
    {
      id: 1,
      title: 'How to learn docker',
      content: ' qjweqwn ejqwne qwne nqwje nqwjen qjwne ojqwne jqwn'
    },
    {
      id: 2,
      title: 'How to learn english',
      content: ' qwen qwen qjen qw'
    }
  ]
]

I have provided the necessary information, so is there any way for the app container to connect to the db container and get the data? Maybe I should edit something more in the docker-compose.yml file?