[javascript mode] Eagerly insert semicolons after return/break/cont

Issue codemirror#5016

Author: marijnh

mode/javascript/javascript.js

@@ -23,13 +23,13 @@ CodeMirror.defineMode("javascript", function(config, parserConfig) {
 
   var keywords = function(){
     function kw(type) {return {type: type, style: "keyword"};}
-    var A = kw("keyword a"), B = kw("keyword b"), C = kw("keyword c");
+    var A = kw("keyword a"), B = kw("keyword b"), C = kw("keyword c"), D = kw("keyword d");
     var operator = kw("operator"), atom = {type: "atom", style: "atom"};
 
     var jsKeywords = {
       "if": kw("if"), "while": A, "with": A, "else": B, "do": B, "try": B, "finally": B,
-      "return": C, "break": C, "continue": C, "new": kw("new"), "delete": C, "void": C, "throw": C, "debugger": C,
-      "var": kw("var"), "const": kw("var"), "let": kw("var"),
+      "return": D, "break": D, "continue": D, "new": kw("new"), "delete": C, "void": C, "throw": C,
+      "debugger": kw("debugger"), "var": kw("var"), "const": kw("var"), "let": kw("var"),
       "function": kw("function"), "catch": kw("catch"),
       "for": kw("for"), "switch": kw("switch"), "case": kw("case"), "default": kw("default"),
       "in": operator, "typeof": operator, "instanceof": operator,
@@ -357,6 +357,8 @@ CodeMirror.defineMode("javascript", function(config, parserConfig) {
     if (type == "var") return cont(pushlex("vardef", value.length), vardef, expect(";"), poplex);
     if (type == "keyword a") return cont(pushlex("form"), parenExpr, statement, poplex);
     if (type == "keyword b") return cont(pushlex("form"), statement, poplex);
+    if (type == "keyword d") return cx.stream.match(/^\s*$/, false) ? cont() : cont(pushlex("stat"), maybeexpression, expect(";"), poplex);
+    if (type == "debugger") return cont(expect(";"));
     if (type == "{") return cont(pushlex("}"), block, poplex);
     if (type == ";") return cont();
     if (type == "if") {
@@ -412,7 +414,7 @@ CodeMirror.defineMode("javascript", function(config, parserConfig) {
     if (atomicTypes.hasOwnProperty(type)) return cont(maybeop);
     if (type == "function") return cont(functiondef, maybeop);
     if (type == "class") return cont(pushlex("form"), classExpression, poplex);
-    if (type == "keyword c" || type == "async") return cont(noComma ? maybeexpressionNoComma : maybeexpression);
+    if (type == "keyword c" || type == "async") return cont(noComma ? expressionNoComma : expression);
     if (type == "(") return cont(pushlex(")"), maybeexpression, expect(")"), poplex, maybeop);
     if (type == "operator" || type == "spread") return cont(noComma ? expressionNoComma : expression);
     if (type == "[") return cont(pushlex("]"), arrayLiteral, poplex, maybeop);

mode/javascript/test.js

@@ -245,6 +245,10 @@
      "[string-2 `${][variable async][operator ++][string-2 }//`];",
      "[string-2 `${]{} [operator /] [string-2 /\\//}`];")
 
+  MT("return_eol",
+     "[keyword return]",
+     "{} [string-2 /5/]")
+
   var ts_mode = CodeMirror.getMode({indentUnit: 2}, "application/typescript")
   function TS(name) {
     test.mode(name, ts_mode, Array.prototype.slice.call(arguments, 1))