Add: Exception option for no-extend-native and no-native-reassign (…

…fixes #2355)

docs/rules/no-extend-native.md

@@ -36,6 +36,21 @@ It *does not* check for any of the following less obvious approaches:
 * `with(Array) { prototype.thing = 'thing'; };`
 * `window.Function.prototype.bind = 'tight';`
 
+## Options
+
+### exceptions
+
+Array of native object names that are permitted to be extended.
+If provided, it must be an `Array`.
+
+```js
+{
+    "rules": {
+        "no-extend-native": [2, {"exceptions": ["Object"]}]
+    }
+}
+```
+
 ## When Not To Use It
 
 You may want to disable this rule when working with polyfills that try to patch older versions of JavaScript with the latest spec, such as those that might `Function.prototype.bind` or `Array.prototype.forEach` in a future-friendly way.

docs/rules/no-native-reassign.md

@@ -54,6 +54,21 @@ String = new Object();
 var String;
 ```
 
+## Options
+
+### exceptions
+
+Array of native object names that are permitted to be reassigned.
+If provided, it must be an `Array`.
+
+```js
+{
+    "rules": {
+        "no-native-reassign": [2, {"exceptions": ["Object"]}]
+    }
+}
+```
+
 ## When Not To Use It
 
 If you are trying to override one of the native objects.

lib/rules/no-extend-native.js

@@ -21,6 +21,16 @@ var BUILTINS = [
 
 module.exports = function(context) {
 
+    var config = context.options[0] || {};
+    var exceptions = config.exceptions || [];
+    var modifiedBuiltins = BUILTINS;
+
+    if (exceptions.length) {
+        modifiedBuiltins = BUILTINS.filter(function(builtIn) {
+            return exceptions.indexOf(builtIn) === -1;
+        });
+    }
+
     return {
 
         // handle the Array.prototype.extra style case
@@ -39,7 +49,7 @@ module.exports = function(context) {
                 return;
             }
 
-            BUILTINS.forEach(function(builtin) {
+            modifiedBuiltins.forEach(function(builtin) {
                 if (lhs.object.object.name === builtin) {
                     context.report(node, builtin + " prototype is read only, properties should not be added.");
                 }
@@ -64,7 +74,7 @@ module.exports = function(context) {
 
                 if (object &&
                     object.type === "Identifier" &&
-                    (BUILTINS.indexOf(object.name) > -1) &&
+                    (modifiedBuiltins.indexOf(object.name) > -1) &&
                     subject.property.name === "prototype") {
 
                     context.report(node, object.name + " prototype is read only, properties should not be added.");

lib/rules/no-native-reassign.js

@@ -11,24 +11,33 @@
 
 module.exports = function(context) {
 
-    var nativeObjects = ["Array", "Boolean", "Date", "decodeURI",
+    var NATIVE_OBJECTS = ["Array", "Boolean", "Date", "decodeURI",
                         "decodeURIComponent", "encodeURI", "encodeURIComponent",
                         "Error", "eval", "EvalError", "Function", "isFinite",
                         "isNaN", "JSON", "Math", "Number", "Object", "parseInt",
                         "parseFloat", "RangeError", "ReferenceError", "RegExp",
                         "String", "SyntaxError", "TypeError", "URIError",
                         "Map", "NaN", "Set", "WeakMap", "Infinity", "undefined"];
+    var config = context.options[0] || {};
+    var exceptions = config.exceptions || [];
+    var modifiedNativeObjects = NATIVE_OBJECTS;
+
+    if (exceptions.length) {
+        modifiedNativeObjects = NATIVE_OBJECTS.filter(function(builtIn) {
+            return exceptions.indexOf(builtIn) === -1;
+        });
+    }
 
     return {
 
         "AssignmentExpression": function(node) {
-            if (nativeObjects.indexOf(node.left.name) >= 0) {
+            if (modifiedNativeObjects.indexOf(node.left.name) >= 0) {
                 context.report(node, node.left.name + " is a read-only native object.");
             }
         },
 
         "VariableDeclarator": function(node) {
-            if (nativeObjects.indexOf(node.id.name) >= 0) {
+            if (modifiedNativeObjects.indexOf(node.id.name) >= 0) {
                 context.report(node, "Redefinition of '{{nativeObject}}'.", { nativeObject: node.id.name });
             }
         }

tests/lib/rules/no-extend-native.js

@@ -30,7 +30,11 @@ eslintTester.addRuleTest("lib/rules/no-extend-native", {
         "this.Object.prototype.toString = 0",
         "with(Object) { prototype.p = 0; }",
         "o = Object; o.prototype.toString = 0",
-        "eval('Object.prototype.toString = 0')"
+        "eval('Object.prototype.toString = 0')",
+        {
+            code: "Object.prototype.g = 0",
+            options: [{exceptions: ["Object"]}]
+        }
     ],
     invalid: [{
         code: "Object.prototype.p = 0",
@@ -62,5 +66,14 @@ eslintTester.addRuleTest("lib/rules/no-extend-native", {
             message: "Array prototype is read only, properties should not be added.",
             type: "CallExpression"
         }]
-    }]
+    },
+        {
+            code: "Number['prototype']['p'] = 0",
+            options: [{exceptions: ["Object"]}],
+            errors: [{
+                message: "Number prototype is read only, properties should not be added.",
+                type: "AssignmentExpression"
+            }]
+        }
+    ]
 });

tests/lib/rules/no-native-reassign.js

@@ -20,10 +20,19 @@ var eslintTester = new ESLintTester(eslint);
 eslintTester.addRuleTest("lib/rules/no-native-reassign", {
     valid: [
         "string = 'hello world';",
-        "var string;"
+        "var string;",
+        {
+            code: "var Object = 0",
+            options: [{exceptions: ["Object"]}]
+        }
     ],
     invalid: [
         { code: "String = 'hello world';", errors: [{ message: "String is a read-only native object.", type: "AssignmentExpression"}] },
-        { code: "var String;", errors: [{ message: "Redefinition of 'String'.", type: "VariableDeclarator"}] }
+        { code: "var String;", errors: [{ message: "Redefinition of 'String'.", type: "VariableDeclarator"}] },
+        {
+            code: "var Object = 0",
+            options: [{exceptions: ["Number"]}],
+            errors: [{ message: "Redefinition of 'Object'.", type: "VariableDeclarator"}]
+        }
     ]
 });