[new-rule] no-restricted-globals

src/configs/all.ts

@@ -51,6 +51,7 @@ export const rules = {
     "no-namespace": true,
     "no-non-null-assertion": true,
     "no-reference": true,
+    "no-restricted-globals": true,
     "no-this-assignment": true,
     "no-var-requires": true,
     "only-arrow-functions": true,

src/rules/noRestrictedGlobalsRule.ts

@@ -0,0 +1,97 @@
+/**
+ * @license
+ * Copyright 2014 Palantir Technologies, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import * as ts from "typescript";
+
+import * as Lint from "../index";
+
+export class Rule extends Lint.Rules.TypedRule {
+    /* tslint:disable:object-literal-sort-keys */
+    public static metadata: Lint.IRuleMetadata = {
+        ruleName: "no-restricted-globals",
+        description: "Disallow specific global variables.",
+        descriptionDetails: Lint.Utils.dedent`
+            Disallowing usage of specific global variables can be useful if you want to allow
+            a set of global variables by enabling an environment, but still want to disallow
+            some of those. For instance, early Internet Explorer versions exposed the current
+            DOM event as a global variable event, but using this variable has been considered
+            as a bad practice for a long time. Restricting this will make sure this variable
+            isn’t used in browser code.
+        `,
+        optionsDescription: "This rule takes a list of strings, where each string is a global to be restricted.",
+        options: {
+            type: "list",
+            items: {type: "string"},
+        },
+        optionExamples: [
+            [
+                true,
+                "name",
+                "length",
+                "event",
+            ],
+        ],
+        type: "functionality",
+        typescriptOnly: false,
+        requiresTypeInfo: true,
+    };
+    /* tslint:enable:object-literal-sort-keys */
+
+    public static FAILURE_STRING(name: string) {
+        return `Unexpected global variable '${name}'. Use local parameter instead.`;
+    }
+
+    public applyWithProgram(sourceFile: ts.SourceFile, program: ts.Program): Lint.RuleFailure[] {
+        const bannedGlobals = new Set(this.ruleArguments as string[]);
+        return this.applyWithFunction(sourceFile, walk, bannedGlobals, program.getTypeChecker());
+    }
+}
+
+function walk(ctx: Lint.WalkContext<Set<string>>, checker: ts.TypeChecker): void {
+    return ts.forEachChild(ctx.sourceFile, function recur(node: ts.Node): void {
+        switch (node.kind) {
+            case ts.SyntaxKind.TypeReference:
+                // Ignore types.
+                return;
+            case ts.SyntaxKind.PropertyAccessExpression:
+                // Ignore `y` in `x.y`, but recurse to `x`.
+                return recur((node as ts.PropertyAccessExpression).expression);
+            case ts.SyntaxKind.Identifier:
+                return checkIdentifier(node as ts.Identifier);
+            default:
+                return ts.forEachChild(node, recur);
+        }
+    });
+
+    function checkIdentifier(node: ts.Identifier): void {
+        if (!ctx.options.has(node.text)) {
+            return;
+        }
+
+        const symbol = checker.getSymbolAtLocation(node);
+        const declarations = symbol === undefined ? undefined : symbol.declarations;
+        if (declarations === undefined || declarations.length === 0) {
+            return;
+        }
+
+        const declaredInLibDom = declarations.some((decl) => decl.getSourceFile().fileName.endsWith(".d.ts"));
+
+        if (declaredInLibDom) {
+            ctx.addFailureAtNode(node, Rule.FAILURE_STRING(node.text));
+        }
+    }
+}

test/rules/no-restricted-globals/test.ts.lint

@@ -0,0 +1,15 @@
+function foo(evt: Event) {
+    let length: number = 1;
+    console.log(length);
+
+    Event.target;
+
+    event.target;
+    ~~~~~ [Unexpected global variable 'event'. Use local parameter instead.]
+}
+
+console.log(length);
+            ~~~~~~  [Unexpected global variable 'length'. Use local parameter instead.]
+
+import { name } from "./foo";
+console.log(name);

test/rules/no-restricted-globals/tsconfig.json

@@ -0,0 +1,8 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "dom"
+        ]
+    }
+}

test/rules/no-restricted-globals/tslint.json

@@ -0,0 +1,10 @@
+{
+  "rules": {
+    "no-restricted-globals": [
+      true,
+      "name",
+      "length",
+      "event"
+    ]
+  }
+}