Use nagetive lookahead

components/prism-javascript.js

@@ -34,7 +34,7 @@ Prism.languages.insertBefore('javascript', 'keyword', {
 	},
 	'parameter': [
 		{
-			pattern: /(function(?:\s+[_$A-Za-z\xA0-\uFFFF][$\w\xA0-\uFFFF]*)?\s*\(\s*)\S(?:[^()]|\([^()]*\))*(?=\s*\))/,
+			pattern: /(function(?:\s+[_$A-Za-z\xA0-\uFFFF][$\w\xA0-\uFFFF]*)?\s*\(\s*)(?!\s)(?:[^()]|\([^()]*\))+?(?=\s*\))/,
 			lookbehind: true,
 			inside: Prism.languages.javascript
 		},
@@ -43,12 +43,12 @@ Prism.languages.insertBefore('javascript', 'keyword', {
 			inside: Prism.languages.javascript
 		},
 		{
-			pattern: /(\(\s*)\S(?:[^()]|\([^()]*\))*(?=\s*\)\s*=>)/,
+			pattern: /(\(\s*)(?!\s)(?:[^()]|\([^()]*\))+?(?=\s*\)\s*=>)/,
 			lookbehind: true,
 			inside: Prism.languages.javascript
 		},
 		{
-			pattern: /((?:\b|\s|^)(?!(?:as|async|await|break|case|catch|class|const|continue|debugger|default|delete|do|else|enum|export|extends|finally|for|from|function|get|if|implements|import|in|instanceof|interface|let|new|null|of|package|private|protected|public|return|set|static|super|switch|this|throw|try|typeof|var|void|while|with|yield)(?![$\w\xA0-\uFFFF]))(?:[_$A-Za-z\xA0-\uFFFF][$\w\xA0-\uFFFF]*\s*)\(\s*)\S(?:[^()]|\([^()]*\))*(?=\s*\)\s*\{)/,
+			pattern: /((?:\b|\s|^)(?!(?:as|async|await|break|case|catch|class|const|continue|debugger|default|delete|do|else|enum|export|extends|finally|for|from|function|get|if|implements|import|in|instanceof|interface|let|new|null|of|package|private|protected|public|return|set|static|super|switch|this|throw|try|typeof|var|void|while|with|yield)(?![$\w\xA0-\uFFFF]))(?:[_$A-Za-z\xA0-\uFFFF][$\w\xA0-\uFFFF]*\s*)\(\s*)(?!\s)(?:[^()]|\([^()]*\))+?(?=\s*\)\s*\{)/,
 			lookbehind: true,
 			inside: Prism.languages.javascript
 		}

prism.js

@@ -743,7 +743,7 @@ Prism.languages.insertBefore('javascript', 'keyword', {
 	},
 	'parameter': [
 		{
-			pattern: /(function(?:\s+[_$A-Za-z\xA0-\uFFFF][$\w\xA0-\uFFFF]*)?\s*\(\s*)\S(?:[^()]|\([^()]*\))*(?=\s*\))/,
+			pattern: /(function(?:\s+[_$A-Za-z\xA0-\uFFFF][$\w\xA0-\uFFFF]*)?\s*\(\s*)(?!\s)(?:[^()]|\([^()]*\))+?(?=\s*\))/,
 			lookbehind: true,
 			inside: Prism.languages.javascript
 		},
@@ -752,12 +752,12 @@ Prism.languages.insertBefore('javascript', 'keyword', {
 			inside: Prism.languages.javascript
 		},
 		{
-			pattern: /(\(\s*)\S(?:[^()]|\([^()]*\))*(?=\s*\)\s*=>)/,
+			pattern: /(\(\s*)(?!\s)(?:[^()]|\([^()]*\))+?(?=\s*\)\s*=>)/,
 			lookbehind: true,
 			inside: Prism.languages.javascript
 		},
 		{
-			pattern: /((?:\b|\s|^)(?!(?:as|async|await|break|case|catch|class|const|continue|debugger|default|delete|do|else|enum|export|extends|finally|for|from|function|get|if|implements|import|in|instanceof|interface|let|new|null|of|package|private|protected|public|return|set|static|super|switch|this|throw|try|typeof|var|void|while|with|yield)(?![$\w\xA0-\uFFFF]))(?:[_$A-Za-z\xA0-\uFFFF][$\w\xA0-\uFFFF]*\s*)\(\s*)\S(?:[^()]|\([^()]*\))*(?=\s*\)\s*\{)/,
+			pattern: /((?:\b|\s|^)(?!(?:as|async|await|break|case|catch|class|const|continue|debugger|default|delete|do|else|enum|export|extends|finally|for|from|function|get|if|implements|import|in|instanceof|interface|let|new|null|of|package|private|protected|public|return|set|static|super|switch|this|throw|try|typeof|var|void|while|with|yield)(?![$\w\xA0-\uFFFF]))(?:[_$A-Za-z\xA0-\uFFFF][$\w\xA0-\uFFFF]*\s*)\(\s*)(?!\s)(?:[^()]|\([^()]*\))+?(?=\s*\)\s*\{)/,
 			lookbehind: true,
 			inside: Prism.languages.javascript
 		}

tests/languages/javascript/function-variable_feature.test

@@ -1,3 +1,4 @@
+foo = function (  ) {}
 foo = function ( x, y) {}
 {foo: function () {}}
 bar = async function baz (x ) {}
@@ -14,6 +15,14 @@ a = function () {}, b = () => {}
 ----------------------------------------------------
 
 [
+	["function-variable", "foo"],
+	["operator", "="],
+	["keyword", "function"],
+	["punctuation", "("],
+	["punctuation", ")"],
+	["punctuation", "{"],
+	["punctuation", "}"],
+
 	["function-variable", "foo"],
 	["operator", "="],
 	["keyword", "function"],
@@ -44,7 +53,7 @@ a = function () {}, b = () => {}
 	["function", "baz"],
 	["punctuation", "("],
 	["parameter", [
-		"x "
+		"x"
 	]],
 	["punctuation", ")"],
 	["punctuation", "{"],
@@ -73,7 +82,7 @@ a = function () {}, b = () => {}
 	["parameter", [
 		"x",
 		["punctuation", ","],
-		" y "
+		" y"
 	]],
 	["punctuation", ")"],
 	["operator", "=>"], " x\r\n",