JSFiddle - React, Tailwind, and code Playground

HTML

<span id="high-unicode">&#x1D465;<!-- mathematical italic small x -->&#xF31E0;<!-- some char from Supplementary Private Use Area-A -->A<!-- char A -->&#x108171;<!-- some char from Supplementary Private Use Area-B --></span>

JavaScript

function decodeUnicode(str) {
	var r = [], i = 0;
	while(i < str.length) {
		var chr = str.charCodeAt(i++);
		if(chr >= 0xD800 && chr <= 0xDBFF) {
			// surrogate pair
			var low = str.charCodeAt(i++);
			r.push(0x10000 + ((chr - 0xD800) << 10) | (low - 0xDC00));
		} else {
			// ordinary character
			r.push(chr);
		}
	}
	return r;
}


var txt = $('#high-unicode').text();
var codes = decodeUnicode(txt);                               
alert(codes);