Console logging for React

Question

I'm super new to React and I'm trying to get it set up for Meteor and piecing stuff together from other sources too.

One of these other sources set up console logging for the app, but I'm going the ES6/JSX way, so just using their code wouldn't work for me (or it doesn't seem like it does).

Some code I found for logging is:

import Logger from 'simple-console-logger';
Logger.configure({level: 'debug'});

But I'm seeing this error:

I also tried using react-logger and react-console-logger to no avail. Here's my code for the latter, which I believe should work.

import {Logger, ConsoleLogger} from 'react-console-logger';
const myLogger = new Logger();
export default class App extends Component {
    render() {
        myLogger.info('something witty');
    }
}

However, myLogger.info('...') is making a call to node_modules/react-console-logger/lib/Logger.js which has it defined as

And this.logger is undefined, although I see it be defined above?

What am I doing wrong? It looks to me like the library has it wrong, but maybe it has something to do with me using JSX files instead of JavaScript?

Answer 1

If you're just after console logging here's what I'd do:

export default class App extends Component {
  componentDidMount() {
    console.log('I was triggered during componentDidMount')
  }

  render() {
    console.log('I was triggered during render')
    return ( 
      <div> I am the App component </div>
    )
  }
}

Shouldn't be any need for those packages just to do console logging.

Answer 2

Here are some more console logging "pro tips":

console.table

var animals = [
    { animal: 'Horse', name: 'Henry', age: 43 },
    { animal: 'Dog', name: 'Fred', age: 13 },
    { animal: 'Cat', name: 'Frodo', age: 18 }
];

console.table(animals);

console.trace

Shows you the call stack for leading up to the console.

You can even customise your consoles to make them stand out

console.todo = function(msg) {
    console.log(‘ % c % s % s % s‘, ‘color: yellow; background - color: black;’, ‘–‘, msg, ‘–‘);
}

console.important = function(msg) {
    console.log(‘ % c % s % s % s’, ‘color: brown; font - weight: bold; text - decoration: underline;’, ‘–‘, msg, ‘–‘);
}

console.todo(“This is something that’ s need to be fixed”);
console.important(‘This is an important message’);

If you really want to level up don't limit your self to the console statement.

Here is a great post on how you can integrate a chrome debugger right into your code editor!

https://hackernoon.com/debugging-react-like-a-champ-with-vscode-66281760037

Answer 3

If you want to log inside JSX, you can create a dummy component
which plugs where you wish to log:

// Some component with JSX and a logger inside
const App = () =>
  <ul>
    {[...Array(4)].map((v, i) => (
      console.log(i), <li key={i}>{i+1}</li>
      )
    )}
    {console.log(123)}
  </ul>

// Render
ReactDOM.render(<App />, root)

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>
<div id="root"></div>

Or for fun, as a Component:

const Console = prop => (
  console[Object.keys(prop)[0]](...Object.values(prop))
  ,null // ➜ React components must return something
)

// Some component with JSX and a logger inside
const App = () =>
  <div>
    <p>imagine this is some component</p>
    <Console log='foo' />
    <p>imagine another component</p>
    <Console warn='bar' />
  </div>

// Render
ReactDOM.render(
  <App />,
  document.getElementById("react")
)

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>
<div id="react"></div>