React Native only supports JSX

[ColinEberhardt]

Unless I am mistake, I should be able to substitute this:

return <Text style={styles.text}>Hello World!</Text>;

With this:

return React.createElement('Text', { style: styles.text }, 'Hello World!');

However, the above causes the application to fail as follows:

[native code]
global code
 URL: http://localhost:8081/Examples/PropertyFinder/PropertyFinderApp.includeRequire.runModule.bundle
 line: 5745
 message: null is not a function (evaluating 'autoGenerateWrapperClass(tag)')"

[vjeux]

Can you try

var Text = React.createFactory(React.Text);
return React.createElement(Text, 'Hello World');

cc @balpert

[ColinEberhardt]

Arggh .. ignore me, I'm being an idiot. This fails:

return React.createElement('Text', { style: styles.text }, 'Hello World!');

Where Text is passed as a string, but this works:

return React.createElement(Text, { style: styles.text }, 'Hello World!');

[vjeux]

The error message is still really bad. Would be nice to throw an exception along the lines of 'You tried to render the element 'Text' but it doesn't exist. You can only use string notation for lowercase components'. Want to submit a pull request that warns against this? It would prevent other people from failing into the same mistake

[sophiebits]

We actually don't use or support string-typed components in React native at all. Would be nice to add a warning for non-lowercase components in React core though.

[ColinEberhardt]

I agree, the error message isn't great. As the react-native behaviour differs from react in this case, one option is to adapt the createElement function, and add the extra parameter type checking here:

https://github.com/facebook/react-native/blob/master/Libraries/ReactIOS/ReactIOS.js#L32

What do you think?

[sophiebits]

In neither case do uppercase tag names make sense, so we can add a warning in React core. We might also want to add some sort of warning for using any string type in React Native.