Create rule S2004: Functions should not be nested too deeply (#3623)

rules/S2004/javascript/metadata.json

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+{
+}

rules/S2004/javascript/rule.adoc

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+== Why is this an issue?
+
+Nested functions refer to the practice of defining a function within another function. These inner functions have access to the variables and parameters of the outer function, creating a closure.
+
+While nesting functions is a common practice in JavaScript, deeply nested functions can make the code harder to read and understand, especially if the functions are long or if there are many levels of nesting.
+
+This can make it difficult for other developers or even yourself to understand and maintain the code.
+
+=== Noncompliant code example
+
+With the default threshold of 3 levels:
+
+[source,javascript]
+----
+function f() {
+  function f_inner() {
+    function f_inner_inner() {
+      function f_inner_inner_inner() { // Noncompliant
+      }
+    }
+  }
+}
+----
+
+== Resources
+
+=== Documentation
+
+* MDN web docs - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Functions#nested_functions_and_closures[Nested functions and closures]

rules/S2004/metadata.json

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 {
+  "title": "Functions should not be nested too deeply",
+  "type": "CODE_SMELL",
+  "code": {
+    "impacts": {
+      "MAINTAINABILITY": "HIGH"
+    },
+    "attribute": "FOCUSED"
+  },
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "20min"
+  },
+  "tags": [
+    "brain-overload"
+  ],
+  "extra": {
+    "replacementRules": [
+
+    ],
+    "legacyKeys": [
+
+    ]
+  },
+  "defaultSeverity": "Critical",
+  "ruleSpecification": "RSPEC-2004",
+  "sqKey": "S2004",
+  "scope": "Main",
+  "defaultQualityProfiles": [
+    "Sonar way"
+  ],
+  "quickfix": "unknown"
 }

rules/S2004/php/metadata.json

@@ -1,34 +1,2 @@
 {
-  "title": "Functions should not be nested too deeply",
-  "type": "CODE_SMELL",
-  "code": {
-    "impacts": {
-      "MAINTAINABILITY": "HIGH"
-    },
-    "attribute": "FOCUSED"
-  },
-  "status": "ready",
-  "remediation": {
-    "func": "Constant\/Issue",
-    "constantCost": "20min"
-  },
-  "tags": [
-    "brain-overload"
-  ],
-  "extra": {
-    "replacementRules": [
-
-    ],
-    "legacyKeys": [
-
-    ]
-  },
-  "defaultSeverity": "Critical",
-  "ruleSpecification": "RSPEC-2004",
-  "sqKey": "S2004",
-  "scope": "Main",
-  "defaultQualityProfiles": [
-    "Sonar way"
-  ],
-  "quickfix": "unknown"
 }