fix: add preceding semicolon in suggestions of no-object-constructor

lib/rules/no-object-constructor.js

@@ -9,12 +9,51 @@
 // Requirements
 //------------------------------------------------------------------------------
 
-const { getVariableByName, isArrowToken } = require("./utils/ast-utils");
+const { getVariableByName, isArrowToken, isClosingBraceToken, isClosingParenToken } = require("./utils/ast-utils");
 
 //------------------------------------------------------------------------------
 // Helpers
 //------------------------------------------------------------------------------
 
+const BREAK_OR_CONTINUE = new Set(["BreakStatement", "ContinueStatement"]);
+
+// Declaration types that must contain a string Literal node at the end.
+const DECLARATIONS = new Set(["ExportAllDeclaration", "ExportNamedDeclaration", "ImportDeclaration"]);
+
+const IDENTIFIER_OR_KEYWORD = new Set(["Identifier", "Keyword"]);
+
+// Keywords that can immediately precede an ExpressionStatement node, mapped to the their node types.
+const NODE_TYPES_BY_KEYWORD = {
+    __proto__: null,
+    break: "BreakStatement",
+    continue: "ContinueStatement",
+    debugger: "DebuggerStatement",
+    do: "DoWhileStatement",
+    else: "IfStatement",
+    return: "ReturnStatement",
+    yield: "YieldExpression"
+};
+
+/*
+ * Before an opening parenthesis, `>` (for JSX), and postfix `++` and `--` always trigger ASI;
+ * the tokens `:`, `;`, `{` and `=>` don't expect a semicolon, as that would count as an empty statement.
+ */
+const PUNCTUATORS = new Set([":", ";", ">", "{", "=>", "++", "--"]);
+
+/*
+ * Statements that can contain an `ExpressionStatement` after a closing parenthesis.
+ * DoWhileStatement is an exception in that it always triggers ASI after the closing parenthesis.
+ */
+const STATEMENTS = new Set([
+    "DoWhileStatement",
+    "ForInStatement",
+    "ForOfStatement",
+    "ForStatement",
+    "IfStatement",
+    "WhileStatement",
+    "WithStatement"
+]);
+
 /**
  * Tests if a node appears at the beginning of an ancestor ExpressionStatement node.
  * @param {ASTNode} node The node to check.
@@ -53,7 +92,8 @@ module.exports = {
 
         messages: {
             preferLiteral: "The object literal notation {} is preferable.",
-            useLiteral: "Replace with '{{replacement}}'."
+            useLiteral: "Replace with '{{replacement}}'.",
+            useLiteralAfterSemicolon: "Replace with '{{replacement}}', add preceding semicolon."
         }
     },
 
@@ -80,6 +120,50 @@ module.exports = {
             return false;
         }
 
+        /**
+         * Determines whether a parenthesized object literal that replaces a specified node needs to be preceded by a semicolon.
+         * @param {ASTNode} node The node to be replaced. This node should be at the start of an `ExpressionStatement` or at the start of the body of an `ArrowFunctionExpression`.
+         * @returns {boolean} Whether a semicolon is required before the parenthesized object literal.
+         */
+        function needsSemicolon(node) {
+            const prevToken = sourceCode.getTokenBefore(node);
+
+            if (!prevToken || prevToken.type === "Punctuator" && PUNCTUATORS.has(prevToken.value)) {
+                return false;
+            }
+
+            const prevNode = sourceCode.getNodeByRangeIndex(prevToken.range[0]);
+
+            if (isClosingParenToken(prevToken)) {
+                return !STATEMENTS.has(prevNode.type);
+            }
+
+            if (isClosingBraceToken(prevToken)) {
+                return (
+                    prevNode.type === "BlockStatement" && prevNode.parent.type === "FunctionExpression" ||
+                    prevNode.type === "ClassBody" && prevNode.parent.type === "ClassExpression" ||
+                    prevNode.type === "ObjectExpression"
+                );
+            }
+
+            if (IDENTIFIER_OR_KEYWORD.has(prevToken.type)) {
+                if (BREAK_OR_CONTINUE.has(prevNode.parent.type)) {
+                    return false;
+                }
+
+                const keyword = prevToken.value;
+                const nodeType = NODE_TYPES_BY_KEYWORD[keyword];
+
+                return prevNode.type !== nodeType;
+            }
+
+            if (prevToken.type === "String") {
+                return !DECLARATIONS.has(prevNode.parent.type);
+            }
+
+            return true;
+        }
+
         /**
          * Reports on nodes where the `Object` constructor is called without arguments.
          * @param {ASTNode} node The node to evaluate.
@@ -93,16 +177,30 @@ module.exports = {
             const variable = getVariableByName(sourceCode.getScope(node), "Object");
 
             if (variable && variable.identifiers.length === 0) {
-                const replacement = needsParentheses(node) ? "({})" : "{}";
+                let replacement;
+                let fixText;
+                let messageId = "useLiteral";
+
+                if (needsParentheses(node)) {
+                    replacement = "({})";
+                    if (needsSemicolon(node)) {
+                        fixText = ";({})";
+                        messageId = "useLiteralAfterSemicolon";
+                    } else {
+                        fixText = "({})";
+                    }
+                } else {
+                    replacement = fixText = "{}";
+                }
 
                 context.report({
                     node,
                     messageId: "preferLiteral",
                     suggest: [
                         {
-                            messageId: "useLiteral",
+                            messageId,
                             data: { replacement },
-                            fix: fixer => fixer.replaceText(node, replacement)
+                            fix: fixer => fixer.replaceText(node, fixText)
                         }
                     ]
                 });