How to Highlight the First Word Automatically in After Effects

How to highlight the first word in your text layer automatically?

1. Create a text layer.
2. Press Animate – Fill Color – RGB.
3. Expand Advanced property and change Units to Index.
4. Alt-click on the End property and paste an expression below.

var userText = text("ADBE Text Document");

userText.length > 0 ? userText.split(/s|W/)[0].length : 0;

How does it work?
The regular expression look for special characters like space, semicolon, enter, etc. and separates the match from the rest of the text.
How to highlight only the first letter?
Remove expression from End property and set the value to 1.