HuyAms

// Dockerfile.dev

FROM node:alpine

WORKDIR '/app'

COPY package.json .
RUN npm install

COPY ..

HuyAms

# Specify a base image
FROM node:alpine

WORKDIR /usr/app

# Install some dependencies
COPY ./package.json ./
RUN npm install
COPY ./ ./

HuyAms

## Prerequisite: Basic knowledge about [React](https://reactjs.org/) and [Refs and the dom](https://reactjs.org/docs/refs-and-the-dom.html#callback-refs) in React

This post is going to talk about what is **useRef** hook and when we can use it.

The first time I learned Hooks, I have so many questions that I need to look for the answers. One of those questions is how I can compare the current state/props with the previous one or handle deep object comparison in **useEffect Hook**. I would only figure it out when I learned about **useRef Hook** then every pieces fall into place.

💪 Let's get started!

## 1. What is useRef hook?