DapperArtisan DapperArtisan - 1 year ago 174
React JSX Question

reactjs Cannot read property 'keys' of undefined

I am learning reactjs through a tutorial and ran into this error. That says "Cannot read property 'keys' of undefined" My code is very minimal so I assume that it has to do with the structure of the language. Does anyone know the problem and a possible solution?

<!DOCTYPE html>


<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.0.1/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.0.1/react-dom.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/babel-core/6.1.19/browser.min.js"></script>
<div id="app"></div>

<script type="text/babel">
var HelloWorld = ReactDOM.createClass({
render: function() {
<h1>Hello World</h1>
<p>This is some text></p>
<HelloWorld />, document.getElementById('app'));

Answer Source

Edit: oddly, after our comments above, I checked to see if it was indeed the babel core version, I am using this one in my fiddle:


The second I switch to your version above I get this:

Uncaught TypeError: Cannot read property 'keys' of undefined

Use React.createClass not ReactDOM.createClass and wrap multiple lines of html in parenthesis like so:

Working Example: https://jsfiddle.net/69z2wepo/38998/

var Hello = React.createClass({
  render: function() {
    return (     
        <h1>Hello World</h1>
        <p>This is some text</p>

  <Hello name="World" />,
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