CODEWITHSUNDEEP
javascriptreactjsreact-proptypes
Orici
Orici

Reputation: 431

PropTypes give me an error with type string

I had an error related with the use of the prop-types library in a running React 16 application after update the node modules.

I created a new React 16 create-react-app project to check this issue and the error occur in the same way.


My code:

index.js file:

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';

ReactDOM.render(
    <App name="Test prop-types"/>, 
    document.getElementById('root')
);

App.js file:

import React from 'react';
import PropTypes from 'prop-types';

function App(props)
{
  let name: PropTypes.string;

  name = (props.name)
    ? props.name
    : "Xxx";

  return (
    <div className="App">
      <header className="App-header">
        <p>Learn React - {name}</p>
      </header>
    </div>
  );
}

export default App;


The error:

Line 8:23:  Parsing error: Unexpected reserved type string

   6 | function App(props) 
   7 | {
>  8 |   let name: PropTypes.string


My package.json content:

{
  "name": "test-prop-types",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "prop-types": "^15.7.2",
    "react": "^16.12.0",
    "react-dom": "^16.12.0",
    "react-scripts": "3.3.0"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  }
}


Doc to use prop-types.

Upvotes: 3

Views: 1752

Answers (1)

Ismael Padilla
Ismael Padilla

Reputation: 5576

You're defining proptypes in the wrong way. Proptypes are defined outside the component definition:

// This is wrong
function App(props) 
    {
        let name: PropTypes.string

Correct way of setting proptypes: 

import React from 'react';
import PropTypes from 'prop-types';

function App(props)
{
  let name = (props.name)
    ? props.name
    : "Xxx";

  return (
    <div className="App">
      <header className="App-header">
        <p>Learn React - {name}</p>
      </header>
    </div>
  );
}

// Setting the proptypes of the `App` component
App.propTypes = {
  name: PropTypes.string
};

export default App;

Upvotes: 2

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