[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 +1,115 @@
+/**
+ * @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.",
+        rationale: Lint.Utils.dedent`
+            \`\`\`ts
+            function broken(evt: Event) {
+                // Meant to do something with \`evt\` but typed it incorrectly.
+                Event.target;  // compiler error
+                event.target;  // should be a lint failure
+            }
+
+            Early Internet Explorer versions exposed the current DOM event as a global variable 'event',
+            but using this variable has been considered a bad practice for a long time.
+            Restricting this will make sure this variable isn’t used in browser code.
+            \`\`\`
+        `,
+        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.
+        `,
+        optionsDescription: Lint.Utils.dedent`
+            This rule takes a list of strings, where each string is a global to be restricted.
+            \`event\`, \`name\` and \`length\` are restricted by default.
+        `,
+        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 a local parameter or variable instead.`;
+    }
+
+    public applyWithProgram(sourceFile: ts.SourceFile, program: ts.Program): Lint.RuleFailure[] {
+        const bannedList = this.ruleArguments.length > 0 ? this.ruleArguments : ["event", "name", "length"];
+        const bannedGlobals = new Set(bannedList);
+        if (sourceFile.isDeclarationFile) {
+            return [];
+        } else {
+            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.ObjectBindingPattern:
+            case ts.SyntaxKind.TypeReference:
+                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 isAmbientGlobal = declarations.some((decl) => decl.getSourceFile().isDeclarationFile);
+
+        if (isAmbientGlobal) {
+            ctx.addFailureAtNode(node, Rule.FAILURE_STRING(node.text));
+        }
+    }
+}

test/rules/no-restricted-globals/custom-global.d.ts

@@ -0,0 +1,2 @@
+declare var badGlobal: any;
+declare var goodGlobal: any;

test/rules/no-restricted-globals/foo.d.ts

@@ -0,0 +1 @@
+export var name: string;

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

@@ -0,0 +1,21 @@
+function typeTest() {
+    type name = any;
+}
+
+function functionTest () {
+    const foo = name;
+
+    function name () {
+
+    }
+}
+
+function interfaceTest() {
+    var foo: name;
+    interface name {}
+}
+
+function classTest() {
+    const foo = new name();
+    class name {}
+}

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

@@ -0,0 +1,10 @@
+console.log(name);
+            ~~~~  [Unexpected global variable 'name'. Use a local parameter or variable instead.]
+
+namespace A {
+    const foo = name;
+}
+
+namespace A {
+    export var name = 23;
+}

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

@@ -0,0 +1,21 @@
+function foo(evt: Event) {
+    let length: number = 1;
+    console.log(length);
+
+    Event.target;
+
+    event.target;
+    ~~~~~ [Unexpected global variable 'event'. Use a local parameter or variable instead.]
+}
+
+console.log(length);
+            ~~~~~~  [Unexpected global variable 'length'. Use a local parameter or variable instead.]
+
+import { name } from "./foo";
+import "./custom-global"
+console.log(name);
+
+console.log(badGlobal);
+            ~~~~~~~~~  [Unexpected global variable 'badGlobal'. Use a local parameter or variable instead.]
+
+console.log(goodGlobal);

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 +1,11 @@
+{
+  "rules": {
+    "no-restricted-globals": [
+      true,
+      "name",
+      "length",
+      "event",
+      "badGlobal"
+    ]
+  }
+}