Code refactor, to make lib more robust and compatible with older node versions

Author: juliovedovatto

lib/resolve-value.js

@@ -14,6 +14,10 @@ function toString(value) {
 	return String(value);
 }
 
+function filterDistinct(value, index, self) {
+	return self.indexOf(value) === index;
+}
+
 // Pass in a value string to parse/resolve and a map of available values
 // and we can figure out the final value
 //
@@ -25,15 +29,19 @@ function toString(value) {
 var resolveValue = function(decl, map, /*optional*/ignorePseudoScope, /*internal debugging*/_debugIsInternal) {
 	var debugIndent = _debugIsInternal ? '\t' : '';
 
+	var matchingVarDecl = undefined;
+	var RE_VAR_FUNC_G = new RegExp(RE_VAR_FUNC.source, 'g');
 	var resultantValue = toString(decl.value);
 	var warnings = [];
+	
 
-	var variablesUsedInValueMap = {};
-	// Use `replace` as a loop to go over all occurrences with the `g` flag
-	resultantValue.replace(new RegExp(RE_VAR_FUNC.source, 'g'), function(match, variableName, fallback) {
-		variablesUsedInValueMap[variableName] = true;
-	});
-	var variablesUsedInValue = Object.keys(variablesUsedInValueMap);
+	// match all variables first, to gather all available variables in decl.value
+	var variablesUsedInValue = [];
+	while ((matchingVarDecl = RE_VAR_FUNC_G.exec(resultantValue))) {
+		variablesUsedInValue.push(matchingVarDecl[1]);
+	}
+	// remove duplicates from array
+	variablesUsedInValue = variablesUsedInValue.filter(filterDistinct);
 
 	//console.log(debugIndent, (_debugIsInternal ? '' : 'Try resolving'), generateScopeList(decl.parent, true), `ignorePseudoScope=${ignorePseudoScope}`, '------------------------');
 
@@ -43,14 +51,16 @@ var resolveValue = function(decl, map, /*optional*/ignorePseudoScope, /*internal
 	// var() = var( <custom-property-name> [, <any-value> ]? )
 	// matches `name[, fallback]`, captures "name" and "fallback"
 	// See: http://dev.w3.org/csswg/css-variables/#funcdef-var
-	var match;
-	while (match = balanced('var(', ')', resultantValue)) {
+	while ((matchingVarDecl = balanced('var(', ')', resultantValue))) {
 		var matchingVarDeclMapItem = undefined;
 
-		// split comma to find variable name and fallback value
-		match.body = match.body.split(',');
+		// Split at the comma to find variable name and fallback value
+		// There may be other commas in the values so this isn't necessary just 2 pieces
+		var variableFallbackSplitPieces = matchingVarDecl.body.split(',');
+
 		// get variable name and fallback, filtering empty items
-		var [ variableName, fallback ] = [ match.body.shift(), match.body.join(',') ].map(item => item.trim()).filter(item => !!item);
+		var variableName = variableFallbackSplitPieces[0].trim();
+		var fallback = variableFallbackSplitPieces.length > 1 ? variableFallbackSplitPieces.slice(1).join(',').trim() : undefined;
 
 		(map[variableName] || []).forEach(function(varDeclMapItem) {
 			// Make sure the variable declaration came from the right spot
@@ -103,7 +113,7 @@ var resolveValue = function(decl, map, /*optional*/ignorePseudoScope, /*internal
 		}
 
 		// replace original declaration
-		resultantValue = `${match.pre || ''}${replaceValue}${match.post || ''}`;
+		resultantValue = (matchingVarDecl.pre || '') + replaceValue + (matchingVarDecl.post || '')
 	}
 
 	return {