How to add a non-breaking space to a rich text field? Seems like a basic question but I can’t figure out a way to do this out of the box, or reference to it in the Redactor docs. ‘&amp;nbsp;’ always gets stripped out.
What about using CSS white-space: nowrap; instead of &amp;nbsp; characters? I guess that's semantically more correct and this also allows you to prevent your text to break at any other character (great for phone numbers etc.).

CSS:

.nobr {
  white-space: nowrap;
}


Markup:

&lt;p&gt;my phone number is &lt;span class="nobr"&gt;+1 800-275-8777&lt;/span&gt;&lt;/p&gt;


To add this easily to your Redactor fields markup, have a look at the inline format API or the formattingAdd config setting (I actually had mixed experiences with that setting).

If you'd like to be able to add this with the click of a button, I also just added this to my Redactor Inline Styles plugin, which is a collection of (optional) buttons to apply inline styles to your Redactor texts (Quotes, Code, etc.).