New: Add no-whitespace-before-property rule (fixes eslint#1086)

conf/eslint.json

@@ -89,6 +89,7 @@
         "no-sequences": 0,
         "no-shadow": 0,
         "no-shadow-restricted-names": 0,
+        "no-whitespace-before-property": 0,
         "no-spaced-func": 0,
         "no-sparse-arrays": 2,
         "no-sync": 0,

docs/rules/README.md

@@ -182,6 +182,7 @@ These rules are purely matters of style and are quite subjective.
 * [no-new-object](no-new-object.md) - disallow the use of the `Object` constructor
 * [no-plusplus](no-plusplus.md) - disallow use of unary operators, `++` and `--`
 * [no-restricted-syntax](no-restricted-syntax.md) - disallow use of certain syntax in code
+* [no-whitespace-before-property](no-whitespace-before-property.md) - disallow whitespace before properties
 * [no-spaced-func](no-spaced-func.md) - disallow space between function identifier and application (fixable)
 * [no-ternary](no-ternary.md) - disallow the use of ternary operators
 * [no-trailing-spaces](no-trailing-spaces.md) - disallow trailing whitespace at the end of lines (fixable)

docs/rules/no-whitespace-before-property.md

@@ -0,0 +1,70 @@
+# Disallow whitespace before properties (no-whitespace-before-property)
+
+JavaScript allows whitespace between objects and their properties. However, inconsistent spacing can make code harder to read and can lead to errors.
+
+```js
+foo. bar
+
+foo . bar
+
+foo [bar]
+```
+
+## Rule Details
+
+This rule disallows whitespace around dot or brackets before properties of objects if they are on the same line. It does not alert for whitespace when the object and property are on separate lines, as it is common to add newlines to longer chains of properties to improve readability:
+
+```js
+foo
+  .bar()
+  .baz()
+  .qux()
+```
+
+The following patterns are considered problems when this rule is turned on:
+
+```js
+/*eslint no-whitespace-before-property: 2*/
+
+foo [bar]
+
+foo. bar
+
+foo .bar
+
+foo. bar. baz
+
+foo. bar()
+  .baz()
+
+foo
+  .bar(). baz()
+```
+
+And the following patterns are not considered problems:
+
+```js
+/*eslint no-whitespace-before-property: 2*/
+
+foo.bar
+
+foo[bar]
+
+foo.bar.baz
+
+foo
+  .bar().baz()
+
+foo
+  .bar()
+  .baz()
+
+foo.
+  bar().
+  baz()
+```
+
+## When Not To Use It
+
+Turn this rule off if you do not care about allowing whitespace around dot or brackets before properties of objects if they are on the same line.
+

lib/rules/no-whitespace-before-property.js

@@ -0,0 +1,43 @@
+/**
+ * @fileoverview Rule to disallow whitespace before properties
+ * @author Kai Cataldo
+ * @copyright 2015 Kai Cataldo. All rights reserved.
+ * See LICENSE file in root directory for full license.
+ */
+"use strict";
+
+var astUtils = require("../ast-utils");
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = function(context) {
+    var sourceCode = context.getSourceCode();
+
+    //--------------------------------------------------------------------------
+    // Public
+    //--------------------------------------------------------------------------
+
+    return {
+        MemberExpression: function(node) {
+            var obj = node.object;
+            var prop = node.property;
+
+            if (astUtils.isTokenOnSameLine(obj, prop)) {
+                if (sourceCode.isSpaceBetweenTokens(obj, prop)) {
+                    context.report({
+                        node: node,
+                        message: "Unexpected whitespace before property \"{{ propName }}\".",
+                        data: {
+                            propName: prop.name
+                        }
+                    });
+                }
+            }
+        }
+    };
+};
+
+module.exports.schema = [];
+

tests/lib/rules/no-whitespace-before-property.js

@@ -0,0 +1,244 @@
+/**
+ * @fileoverview Rule to disallow whitespace before properties
+ * @author Kai Cataldo
+ * @copyright 2015 Kai Cataldo. All rights reserved.
+ * See LICENSE file in root directory for full license.
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+var rule = require("../../../lib/rules/no-whitespace-before-property"),
+    RuleTester = require("../../../lib/testers/rule-tester");
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+var ruleTester = new RuleTester();
+
+ruleTester.run("no-whitespace-before-property", rule, {
+
+    valid: [
+        "foo.bar",
+        "foo.bar()",
+        "foo[bar]",
+        "foo\n.bar",
+        "foo.\nbar",
+        "foo\n.bar()",
+        "foo.\nbar()",
+        "foo\n[bar]",
+        "foo.\n bar",
+        "foo\n. bar",
+        "foo.\n bar()",
+        "foo\n. bar()",
+        "foo\n [bar]",
+        "foo.\n\tbar",
+        "foo\n.\tbar",
+        "foo.\n\tbar()",
+        "foo\n.\tbar()",
+        "foo\n\t[bar]",
+        "foo.bar.baz",
+        "foo\n.bar\n.baz",
+        "foo.\nbar.\nbaz",
+        "foo.bar().baz()",
+        "foo\n.bar()\n.baz()",
+        "foo.\nbar().\nbaz()",
+        "foo\n.bar\n[baz]",
+        "foo\n .bar\n .baz",
+        "foo.\n bar.\n baz",
+        "foo\n .bar()\n .baz()",
+        "foo.\n bar().\n baz()",
+        "foo\n .bar\n [baz]",
+        "foo\n\t.bar\n\t.baz",
+        "foo.\n\tbar.\n\tbaz",
+        "foo\n\t.bar()\n\t.baz()",
+        "foo.\n\tbar().\n\tbaz()",
+        "foo\n\t.bar\n\t[baz]"
+    ],
+
+    invalid: [
+        {
+            code: "foo. bar",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo .bar",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo [bar]",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo. bar. baz",
+            errors: ["Unexpected whitespace before property \"baz\".", "Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo .bar. baz",
+            errors: ["Unexpected whitespace before property \"baz\".", "Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo [bar] [baz]",
+            errors: ["Unexpected whitespace before property \"baz\".", "Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo [bar][baz]",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo[bar] [baz]",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+        {
+            code: "foo.bar [baz]",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+        {
+            code: "foo. bar[baz]",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo[bar]. baz",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+
+        // tabs
+        {
+            code: "foo\t.bar",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo.\tbar",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo\t.bar()",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo.\tbar()",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo\t[bar]",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo.\tbar.\tbaz",
+            errors: ["Unexpected whitespace before property \"baz\".", "Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo\t.bar.\tbaz",
+            errors: ["Unexpected whitespace before property \"baz\".", "Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo.\tbar().\tbaz()",
+            errors: ["Unexpected whitespace before property \"baz\".", "Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo\t.bar().\tbaz()",
+            errors: ["Unexpected whitespace before property \"baz\".", "Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo\t[bar]\t[baz]",
+            errors: ["Unexpected whitespace before property \"baz\".", "Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo\t[bar][baz]",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo[bar]\t[baz]",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+        {
+            code: "foo.bar\t[baz]",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+        {
+            code: "foo.\tbar[baz]",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo[bar].\tbaz",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+
+        // newlines
+        {
+            code: "foo [bar]\n .baz",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo. bar\n .baz",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo .bar\n.baz",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo.\n bar. baz",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+        {
+            code: "foo.\nbar . baz",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+        {
+            code: "foo. bar()\n .baz()",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo .bar()\n.baz()",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo.\n bar(). baz()",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+        {
+            code: "foo.\nbar() . baz()",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+        {
+            code: "foo\t[bar]\n\t.baz",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo.\tbar\n\t.baz",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo\t.bar\n.baz",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo.\n\tbar.\tbaz",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+        {
+            code: "foo.\nbar\t.\tbaz",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+        {
+            code: "foo.\tbar()\n\t.baz()",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo\t.bar()\n.baz()",
+            errors: ["Unexpected whitespace before property \"bar\"."]
+        },
+        {
+            code: "foo.\n\tbar().\tbaz()",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        },
+        {
+            code: "foo.\nbar()\t.\tbaz()",
+            errors: ["Unexpected whitespace before property \"baz\"."]
+        }
+    ]
+});