update README for JavaScript

code/JavaScript/Arrays/arrays.js

@@ -0,0 +1,17 @@
+let cats = ['Bob', 'Willy', 'Mini'];
+
+// pop(): Remove an item from the end of an array
+// pop() returns the removed item
+cats.pop(); // ['Bob', 'Willy']
+
+// push(): Add items to the end of an array
+// push() returns the new array length
+cats.push('Mini'); // ['Bob', 'Willy', 'Mini']
+
+// shift(): Remove an item from the beginning of an array
+// shift() returns the removed item
+cats.shift(); // ['Willy', 'Mini']
+
+// unshift(): Add items to the beginning of an array
+// unshift() returns the new array length.
+cats.unshift('Puff', 'George'); // ['Puff', 'George', 'Willy', 'Mini']

code/JavaScript/Arrays/forEach.js

@@ -0,0 +1,9 @@
+// arr.forEach(function callback(currentValue, index, array) {
+  // your iterator
+// }[, thisArg]);
+
+Синтаксис
+
+arr.forEach(function callback(currentValue, index, array) {
+  //your iterator
+}[, thisArg]);