Question: I had been previously using [Allan Hortle's JSX package](https://github.com/allanhortle/JSX) until I ran into an issue with how it handled syntax highlighting. I then noticed that there is an official package, [sublime-react](https://github.com/reactjs/sublime-react).

With Allan Hortle's package, he included a snippet in the `Preferences > Key Bindings – User` for enabling Emmet functionality that looks like this:

```
{
    "keys": ["tab"],
    "command": "expand_abbreviation_by_tab", 
    "context": [
        {
            "operand": "source.js.jsx", 
            "operator": "equal", 
            "match_all": true, 
            "key": "selector"
        }
    ]
}

```

This snippet doesn't appear to work with the official sublime-react package. It seems to be something to modify with the key bindings but an initial perusal of the Sublime documentation yielded no light on the subject. Help?

Answer: 
If you type `shift+super+p` in a file it will let you see the current selection's context in the bottom left.

The first word is always the base file type. (`source.js`, `text.html`) In the case of the [JSX](https://github.com/allanhortle/JSX) I chose to change this to `source.js.jsx`. This is because before it is compiled JSX really isn't javascript, though it does look rather similar. There are plenty of completions and sublime sugar that you'd like to have happen in JSX but not JS. [sublime-react](https://github.com/reactjs/sublime-react) on the other hand uses plain old `source.js`. 

So this snippet you have is right you just need to replace `source.js.jsx` with `source.js`
In 2021 it's not necessary to configure anything as Emmet has support for JSX files by default.

Obviously you need to install the [JSX language definition](https://packagecontrol.io/packages/JSX) from package control after installing Emmet.

Now `TAB` will work but only when the HTML tag is prefixed with a `<`. For example `<div`. To change this behavior open the Emmet settings and change this setting to `false`:

```
"jsx_prefix": false

```

To open the Emmet settings either use the File menu as show in the image below, or open the command palette (CMD+Shift+P on macOS) and write "Emmet settings".

[![enter image description here](https://i.stack.imgur.com/JIjJV.jpg)](https://i.stack.imgur.com/JIjJV.jpg)