Center (proportional font) text in an HTML5 canvas

Question

I would like to be able to center single lines of text within rectangular areas I can calculate. The one thing I have expected to do in 2D geometry on a canvas is to center

Answer 1

What you do is render your text off-screen using a negative text-indent, then grab the size.

text-indent: -9999px

See: hiding text using "text-indent"