esc-fmt-same-string-edges
Format 2 strings, human readable, easy compare, highlight beginning/middle/end (if applicable) same/different parts, algorithm/function, visualize/highlight, match unchanged context. Fast and minimal, zero dependencies, supply your own formatting function
domx-stringify
DOMx extension that makes it easy to convert DOM structures to strings, both plain and marked up for highlighting.
pretty-html-log
pretty-html-log is a npm module that pretty prints a raw html string to the console. It indents and highlights your code.