Understanding the useRef Hook in React

The useRefHook is an essential tool in React that allows us to store values between renders, directly access DOM elements, and avoid unnecessary re-renders. It’s often compared to the useStateHook but serves a different purpose.

What is the useRef Hook?

The useRef Hook creates a reference to a value or DOM element that persists between component renders. The key difference between useRefand useStateis that updating the useRefvalue does not trigger a re-render, which can be particularly useful in certain scenarios.

1. It does not cause re-renders when its value changes.
2. It can be used to store mutable values.
3. It can be used to directly access DOM elements.

Basic Syntax

const refContainer = useRef(initialValue);

Example 1: Persisting Values Between Renders

import React, { useRef, useEffect } from "react";

function RenderCount() {
  const renderCount = useRef(1);

  useEffect(() => {
    renderCount.current = renderCount.current + 1;
  });

  // Inline styles
  const containerStyle = {
    display: "flex",
    justifyContent: "center",
    alignItems: "center",
    height: "100vh",
    backgroundColor: "#f4f4f4",
  };

  const headingStyle = {
    fontSize: "2rem",
    color: "#333",
    fontFamily: "Arial, sans-serif",
    backgroundColor: "#fff",
    padding: "20px",
    borderRadius: "8px",
    boxShadow: "0 4px 8px rgba(0, 0, 0, 0.1)",
  };

  return (
    <div style={containerStyle}>
      <h1 style={headingStyle}>
        This component has rendered {renderCount.current} times.
      </h1>
    </div>
  );
}

export default RenderCount;

Output

Example 2: Accessing DOM Elements

import React, { useState, useRef } from "react";

function Timer() {
  const [seconds, setSeconds] = useState(0);
  const intervalRef = useRef(null);

  // Start the timer
  const startTimer = () => {
    if (!intervalRef.current) {
      intervalRef.current = setInterval(() => {
        setSeconds((prevSeconds) => prevSeconds + 1);
      }, 1000);
    }
  };

  // Stop the timer
  const stopTimer = () => {
    clearInterval(intervalRef.current);
    intervalRef.current = null;
  };

  // Reset the timer
  const resetTimer = () => {
    stopTimer();
    setSeconds(0);
  };

  // Inline styles
  const timerContainerStyle = {
    display: "flex",
    flexDirection: "column",
    alignItems: "center",
    justifyContent: "center",
    height: "100vh",
    backgroundColor: "#f0f2f5", // Light neutral background
  };

  const timerDisplayStyle = {
    fontSize: "3rem",
    color: "#2c3e50", // Dark blue-gray for a professional look
  };

  const buttonStyle = {
    padding: "10px 20px",
    margin: "10px",
    fontSize: "1rem",
    backgroundColor: "#2980b9", // Professional blue
    color: "white",
    border: "none",
    borderRadius: "5px",
    cursor: "pointer",
    transition: "background-color 0.3s ease-in-out",
  };

  const buttonHoverStyle = {
    backgroundColor: "#1a5276", // Darker shade for hover effect
  };

  return (
    <div style={timerContainerStyle}>
      <h1 style={timerDisplayStyle}>{seconds} seconds</h1>
      <div>
        <button
          style={buttonStyle}
          onClick={startTimer}
          onMouseOver={(e) => (e.currentTarget.style.backgroundColor = buttonHoverStyle.backgroundColor)}
          onMouseOut={(e) => (e.currentTarget.style.backgroundColor = buttonStyle.backgroundColor)}
        >
          Start
        </button>
        <button
          style={buttonStyle}
          onClick={stopTimer}
          onMouseOver={(e) => (e.currentTarget.style.backgroundColor = buttonHoverStyle.backgroundColor)}
          onMouseOut={(e) => (e.currentTarget.style.backgroundColor = buttonStyle.backgroundColor)}
        >
          Stop
        </button>
        <button
          style={buttonStyle}
          onClick={resetTimer}
          onMouseOver={(e) => (e.currentTarget.style.backgroundColor = buttonHoverStyle.backgroundColor)}
          onMouseOut={(e) => (e.currentTarget.style.backgroundColor = buttonStyle.backgroundColor)}
        >
          Reset
        </button>
      </div>
    </div>
  );
}

export default Timer;

Output

When to Use useRef Instead of useState

Here are some scenarios where useRefis more appropriate than useState:

When you need to store a value that doesn’t need to trigger a re-render when updated (e.g., timers, counters, or tracking renders).
When you need to directly access or modify DOM elements without causing a re-render.