Iteration and recursion code in js/ts (#703)

* feat(JS and TS):add the section of iteration and recursion

* feat(JS and TS):add the section of iteration and recursion

* feat(JS and TS):add the section of iteration and recursion

codes/javascript/chapter_computational_complexity/iteration.js

@@ -0,0 +1,70 @@
+/**
+ * File: iteration.js
+ * Created Time: 2023-08-28
+ * Author: Gaofer Chou (gaofer-chou@qq.com)
+ */
+
+/* for 循环 */
+function forLoop(n) {
+    let res = 0;
+    // 循环求和 1, 2, ..., n-1, n
+    for (let i = 1; i <= n; i++) {
+        res += i;
+    }
+    return res;
+}
+
+/* while 循环 */
+function whileLoop(n) {
+    let res = 0;
+    let i = 1; // 初始化条件变量
+    // 循环求和 1, 2, ..., n-1, n
+    while (i <= n) {
+        res += i;
+        i++; // 更新条件变量
+    }
+    return res;
+}
+
+/* while 循环（两次更新） */
+function whileLoopII(n) {
+    let res = 0;
+    let i = 1; // 初始化条件变量
+    // 循环求和 1, 4, ...
+    while (i <= n) {
+        res += i;
+        // 更新条件变量
+        i++;
+        i *= 2;
+    }
+    return res;
+}
+
+/* 双层 for 循环 */
+function nestedForLoop(n) {
+    let res = '';
+    // 循环 i = 1, 2, ..., n-1, n
+    for (let i = 1; i <= n; i++) {
+        // 循环 j = 1, 2, ..., n-1, n
+        for (let j = 1; j <= n; j++) {
+            res += `(${i}, ${j}), `;
+        }
+    }
+    return res;
+}
+
+/* Driver Code */
+const n = 5;
+let res;
+
+res = forLoop(n);
+console.log(`for 循环的求和结果 res = ${res}`);
+
+res = whileLoop(n);
+console.log(`while 循环的求和结果 res = ${res}`);
+
+res = whileLoopII(n);
+console.log(`while 循环（两次更新）求和结果 res = ${res}`);
+
+const resStr = nestedForLoop(n);
+console.log(`双层 for 循环的遍历结果 ${resStr}`);