TLDNR: \p{Egyptian_Hieroglyphs}
Javascript
Egyptian_Hieroglyphs belong to the "astral" plane that uses more than 16 bits to encode a character. Javascript, as of ES5, doesn't support astral planes (more on that) therefore you have to use surrogate pairs. The first surrogate is
U+13000 = d80c dc00
the last one is
U+1342E = d80d dc2e
that gives
re = /(\uD80C[\uDC00-\uDFFF]|\uD80D[\uDC00-\uDC2E])+/g
t = document.getElementById("pyramid").innerHTML
document.write("Found
" + t.match(re))