added destructuring for rest parameters and formal parameters (#20759)

guide/english/javascript/arguments/index.md

@@ -95,7 +95,29 @@ The arguments object is not available inside the body of an arrow function.
 The rest parameter must always come as the last argument in your function definition.  
     ```function getIntoAnArgument(arg1, arg2, arg3, ...restOfArgs  /*no more arguments allowed here*/) {
         //function body
-    }```   
+    }```
+    
+so doing this should throw a SyntaxError: Rest parameter must be last formal parameter 
+    ```function invalidRestUse(...args, arg1, arg2){
+    }```
 
+Rest parameters can be destuctured and unpacked into distinct variables
+    ```
+    function restDestructuring(...[a, b, c]){
+        return a + b + c;
+    }
+    
+    restDestructuring(1, 2, 3);  // 6
+    ```
+### ES6 destructuring of arrays in formal parameter
 
+With the new destructuring feature we can even go one step ahead when passing an array to a function and break down its elements as variables.
+    ```
+    function arrayDestructuring([a, b, c]){
+        return a + b + c;    
+    }
 
+    arrayDestructuring([1,2]) //Nan , as 1 + 2 + undefined = NaN 
+    arrayDestructuring([1,2,3]) // 6
+    arrayDestructuring([1,2,3,4,5]) // 6  additional elements will be ignored
+    ```