Github vs npm markdown, escaping vertical bar

For a table cell in Github markdown, you have to escape | with \ to avoid having it interpreted as the next cell. Once you escape it, everything is fine e.g. https://github.com/russellw/clause-normal-form the entries for Nor and Or.

For a table cell in npm markdown, this doesn't work; the \ comes out in the display e.g. https://www.npmjs.com/package/clause-normal-form the entries for Nor and Or.

How to escape | in a table in a readme, such that Github and npm will both display it correctly?

via rwallace