New: array-element-newline rule (fixes #6075) (#8375)

conf/eslint-recommended.js

@@ -17,6 +17,7 @@ module.exports = {
         "array-bracket-newline": "off",
         "array-bracket-spacing": "off",
         "array-callback-return": "off",
+        "array-element-newline": "off",
         "arrow-body-style": "off",
         "arrow-parens": "off",
         "arrow-spacing": "off",

docs/rules/array-element-newline.md

@@ -0,0 +1,240 @@
+# enforce line breaks between array elements (array-element-newline)
+
+A number of style guides require or disallow line breaks between array elements.
+
+## Rule Details
+
+This rule enforces line breaks between array elements.
+
+## Options
+
+This rule has either a string option:
+
+* `"always"` (default) requires line breaks between array elements
+* `"never"` disallows line breaks between array elements
+
+Or an object option (Requires line breaks if any of properties is satisfied. Otherwise, disallows line breaks):
+
+* `"multiline": <boolean>` requires line breaks if there are line breaks inside elements. If this is false, this condition is disabled.
+* `"minItems": <number>` requires line breaks if the number of elements is at least the given integer. If this is 0, this condition will act the same as the option `"always"`. If this is `null` (the default), this condition is disabled.
+
+### always
+
+Examples of **incorrect** code for this rule with the default `"always"` option:
+
+```js
+/*eslint array-element-newline: ["error", "always"]*/
+
+var c = [1, 2];
+var d = [1, 2, 3];
+var e = [
+    function foo() {
+        dosomething();
+    }, function bar() {
+        dosomething();
+    }
+];
+```
+
+Examples of **correct** code for this rule with the default `"always"` option:
+
+```js
+/*eslint array-element-newline: ["error", "always"]*/
+
+var a = [];
+var b = [1];
+var c = [1,
+    2];
+var d = [1,
+    2,
+    3];
+var e = [
+    function foo() {
+        dosomething();
+    },
+    function bar() {
+        dosomething();
+    }
+];
+```
+
+### never
+
+Examples of **incorrect** code for this rule with the default `"never"` option:
+
+```js
+/*eslint array-element-newline: ["error", "never"]*/
+
+var c = [
+    1,
+    2
+];
+var d = [
+    1,
+    2,
+    3
+];
+var e = [
+    function foo() {
+        dosomething();
+    },
+    function bar() {
+        dosomething();
+    }
+];
+```
+
+Examples of **correct** code for this rule with the `"never"` option:
+
+```js
+/*eslint array-element-newline: ["error", "never"]*/
+
+var a = [];
+var b = [1];
+var c = [1, 2];
+var d = [1, 2, 3];
+var e = [
+    function foo() {
+        dosomething();
+    }, function bar() {
+        dosomething();
+    }
+];
+```
+
+### multiline
+
+Examples of **incorrect** code for this rule with the `{ "multiline": true }` option:
+
+```js
+/*eslint array-element-newline: ["error", { "multiline": true }]*/
+
+var d = [1,
+    2, 3];
+var e = [
+    function foo() {
+        dosomething();
+    }, function bar() {
+        dosomething();
+    }
+];
+```
+
+Examples of **correct** code for this rule with the `{ "multiline": true }` option:
+
+```js
+/*eslint array-element-newline: ["error", { "multiline": true }]*/
+
+var a = [];
+var b = [1];
+var c = [1, 2];
+var d = [1, 2, 3];
+var e = [
+    function foo() {
+        dosomething();
+    },
+    function bar() {
+        dosomething();
+    }
+];
+```
+
+### minItems
+
+Examples of **incorrect** code for this rule with the `{ "minItems": 3 }` option:
+
+```js
+/*eslint array-element-newline: ["error", { "minItems": 3 }]*/
+
+var c = [1,
+    2];
+var d = [1, 2, 3];
+var e = [
+    function foo() {
+        dosomething();
+    },
+    function bar() {
+        dosomething();
+    }
+];
+```
+
+Examples of **correct** code for this rule with the `{ "minItems": 3 }` option:
+
+```js
+/*eslint array-element-newline: ["error", { "minItems": 3 }]*/
+
+var a = [];
+var b = [1];
+var c = [1, 2];
+var d = [1,
+    2,
+    3];
+var e = [
+    function foo() {
+        dosomething();
+    }, function bar() {
+        dosomething();
+    }
+];
+```
+
+### multiline and minItems
+
+Examples of **incorrect** code for this rule with the `{ "multiline": true, "minItems": 3 }` options:
+
+```js
+/*eslint array-element-newline: ["error", { "multiline": true, "minItems": 3 }]*/
+
+var c = [1,
+2];
+var d = [1, 2, 3];
+var e = [
+    function foo() {
+        dosomething();
+    }, function bar() {
+        dosomething();
+    }
+];
+```
+
+Examples of **correct** code for this rule with the `{ "multiline": true, "minItems": 3 }` options:
+
+```js
+/*eslint array-element-newline: ["error", { "multiline": true, "minItems": 3 }]*/
+
+var a = [];
+var b = [1];
+var c = [1, 2];
+var d = [1,
+    2,
+    3];
+var e = [
+    function foo() {
+        dosomething();
+    },
+    function bar() {
+        dosomething();
+    }
+];
+```
+
+
+## When Not To Use It
+
+If you don't want to enforce linebreaks between array elements, don't enable this rule.
+
+## Compatibility
+
+* **JSCS:** [validateNewlineAfterArrayElements](http://jscs.info/rule/validateNewlineAfterArrayElements)
+
+## Related Rules
+
+* [array-bracket-spacing](array-bracket-spacing.md)
+* [array-bracket-newline](array-bracket-newline.md)
+* [object-property-newline](object-property-newline.md)
+* [object-curly-spacing](object-curly-spacing.md)
+* [object-curly-newline](object-curly-newline.md)
+* [max-statements-per-line](max-statements-per-line.md)
+* [block-spacing](block-spacing.md)
+* [brace-style](brace-style.md)