1onClick={() => {navigator.clipboard.writeText(this.state.textToCopy)}}

1<button 
2  onClick={() =>  navigator.clipboard.writeText('Copy this text to clipboard')}
3>
4  Copy
5</button>

1 <buttononClick={() => navigator.clipboard.writeText("Copy this text to clipboard")}>
2  Copy
3</button>

1<button 
2  onClick={() =>  navigator.clipboard.writeText('Copy this text to clipboard')}
3>
4  Copy
5</button>
6

1import React, { useRef, useState } from 'react';
2
3export default function CopyExample() {
4
5  const [copySuccess, setCopySuccess] = useState('');
6  const textAreaRef = useRef(null);
7
8  function copyToClipboard(e) {
9    textAreaRef.current.select();
10    document.execCommand('copy');
11    // This is just personal preference.
12    // I prefer to not show the the whole text area selected.
13    e.target.focus();
14    setCopySuccess('Copied!');
15  };
16
17  return (
18    <div>
19      {
20       /* Logical shortcut for only displaying the 
21          button if the copy command exists */
22       document.queryCommandSupported('copy') &&
23        <div>
24          <button onClick={copyToClipboard}>Copy</button> 
25          {copySuccess}
26        </div>
27      }
28      <form>
29        <textarea
30          ref={textAreaRef}
31          value='Some text to copy'
32        />
33      </form>
34    </div>
35  );
36}

1onClick={() => {navigator.clipboard.writeText(this.state.textToCopy)}}
2
3<button onClick={() =>  navigator.clipboard.writeText('Copy this text to clipboard')}
4>
5  Copy
6</button>