address PR comments siimon#1

lib/registry.js

@@ -2,6 +2,18 @@
 
 const { getValueAsString } = require('./util');
 
+const ESCAPE_STRING_REPLACE_MAP = {
+	'\\': '\\\\',
+	'\n': '\\n',
+};
+
+const ESCAPE_LABEL_VALUE_REPLACE_MAP = {
+	...ESCAPE_STRING_REPLACE_MAP,
+	'"': '\\\\"',
+};
+
+const ESCAPE_REPLACE_REGEXP = /\\|\n|"/g;
+
 function REPLACE_FUNC(dict) {
 	return char => dict[char] || '';
 }
@@ -15,23 +27,6 @@ class Registry {
 		return 'application/openmetrics-text; version=1.0.0; charset=utf-8';
 	}
 
-	static get ESCAPE_STRING_REPLACE_MAP() {
-		return {
-			'\\': '\\\\',
-			'\n': '\\n',
-		};
-	}
-
-	static get ESCAPE_LABEL_VALUE_REPLACE_MAP() {
-		return Object.assign({}, Registry.ESCAPE_STRING_REPLACE_MAP, {
-			'"': '\\\\"',
-		});
-	}
-
-	static get ESCAPE_REPLACE_REGEXP() {
-		return /\\|\n|"/g;
-	}
-
 	constructor(regContentType = Registry.PROMETHEUS_CONTENT_TYPE) {
 		this._metrics = {};
 		this._collectors = [];
@@ -256,14 +251,14 @@ function escapeLabelValue(str) {
 		return str;
 	}
 
-	return escapeString(str, Registry.ESCAPE_LABEL_VALUE_REPLACE_MAP);
+	return escapeString(str, ESCAPE_LABEL_VALUE_REPLACE_MAP);
 }
 function escapeString(str, extraReplaceDict) {
 	const fullDict = extraReplaceDict
 		? extraReplaceDict
-		: Registry.ESCAPE_STRING_REPLACE_MAP;
+		: ESCAPE_STRING_REPLACE_MAP;
 
-	return str.replace(Registry.ESCAPE_REPLACE_REGEXP, REPLACE_FUNC(fullDict));
+	return str.replace(ESCAPE_REPLACE_REGEXP, REPLACE_FUNC(fullDict));
 }
 function standardizeCounterName(name) {
 	return name.replace(/_total$/, '');