useRef in React

Originally, useRef was used to reference elements in the DOM and it still can be used for it. Yet, it also offers a great alternative to useState, as we will see. useRef can, just like useState, hold values. Here is, what you need to know in short:

• useRef can hold values via the .current attribute
• Altering the values useRef holds DOES NOT trigger a re-render
• The value persist between different renders
• useRef is completely separate from the render-cycle of the component

Using useRef for holding values

useRef is often the ideal alternative when useState doesn’t work. useState might fail to provide a solution in these scenarios, because:

1. The state does not persist when it should do
2. Changing the state causes a re-render and often an endless loop

Here is a good example of useRef for counting the times the component re-rendered:

import React, { useRef, useEffect, useState } from 'react'

export default function App() {
  const rC = useRef(0)
  const [count, setCount] = useState(0)

  useEffect(() => {
    rC.current += 1
  })

  return (
    <>
      <p>Component rendered: {rC.current} times</p>
      <p>Counter: {count}</p>
      <button onClick={() => setCount(count + 1)}>Add</button>
    </>
  )
}

Referencing DOM elements

import React, { useRef, useEffect } from 'react'

export default function App() {
  const pRef = useRef()

  useEffect(() => {
    const el = pRef.current
    console.log(el)
  }, [])

  return (
    <>
      <p ref={pRef}>Hello world!</p>
    </>
  )
}

Logs the following code on the initial render:

HTMLParagraphElement{
    attributes: {…}, innerHTML: "Hello world!", nodeType: 1, tagName: "p"
}

Differences of useRef and useState

To sum up, here are a couple differences between both hooks, from the view point of useState:

• Values are accessed with .current in useRef, instead of with a single function
• Updating values does not force a re-render, therefore, useRef will not cause the typical infinite re-render bug
• Setting and altering values in useRef is done with assigning to .current