diff --git a/js/lib/core.js b/js/lib/core.js
index 4f96d94..aacc17d 100644
--- a/js/lib/core.js
+++ b/js/lib/core.js
@@ -1,38 +1,52 @@
-if (!String.prototype.size) {
-  Object.defineProperty(String.prototype, 'size', {
-    get() {
-      var n = 0
-      for (let it of this) {
-        n++
-      }
-      return n
-    }
-  })
+/**
+ * 增强版 String
+ */
+export class SString {
+  #origin = ''
+  #list = []
 
-  Object.defineProperty(String.prototype, 'at16', {
-    value(n) {
-      var tmp = []
-      for (let it of this) {
-        tmp.push(it)
-      }
-      return tmp[n]
+  constructor(str = '') {
+    this.#origin = str
+
+    for (let it of str) {
+      this.#list.push(it)
     }
-  })
-  Object.defineProperty(String.prototype, 'split16', {
-    value(pipe) {
-      if (pipe === '') {
-        var tmp = []
-        for (let it of this) {
-          tmp.push(it)
-        }
-        return tmp
-      } else {
-        return this.split(pipe)
+  }
+
+  get length() {
+    return this.#list.length
+  }
+
+  at(index = 0) {
+    if (this.length > 0) {
+      while (index < 0) {
+        index += this.length
+      }
+      return this.#list[index]
+    }
+  }
+
+  split() {
+    return this.#list
+  }
+
+  forEach(callback) {
+    for (let i in this.#list) {
+      if (callback(this.#list[i], i) === false) {
+        break
       }
     }
-  })
+    return this
+  }
+
+  toString() {
+    return this.#origin
+  }
 }
 
+/**
+ * 特殊版 Enum
+ */
 export class Enum {
   #dict_k = Object.create(null)
   #dict_v = Object.create(null)