Escape HTML entities

escapeHtml.js

const htmlEntities = {
	'<': '&lt;',
	'>': '&gt;',
	'"': '&quot;',
	"'": "&#39;",
	'&': "&amp;"
};
	
const htmlCharExpr = new RegExp(`[${Object.keys(htmlEntities).join('')}]`, 'g');

function escapeHtml (string) {
	return string.replace(htmlCharExpr, char => htmlEntities[char]);
}

function escapeHtmlTest () {
	const string = `&><'"“‘”’test`;
	const escaped = escapeHtml(string);
	console.log("Escaped: %s", escaped);
	console.assert(escaped === `&amp;&gt;&lt;&#39;&quot;“‘”’test`, "Expected &amp;&gt;&lt;&#39;&quot“‘”’test, got %s", escaped);
}