docs: Add docs for isLength

docs/.vitepress/zh_hans.mts

@@ -147,6 +147,7 @@ function sidebar(): DefaultTheme.Sidebar {
           text: '谓词',
           items: [
             { text: 'isEqual', link: '/zh_hans/reference/predicate/isEqual' },
+            { text: 'isLength', link: '/zh_hans/reference/predicate/isLength' },
             { text: 'isPlainObject', link: '/zh_hans/reference/predicate/isPlainObject' },
             { text: 'isNil', link: '/zh_hans/reference/predicate/isNil' },
             { text: 'isNotNil', link: '/zh_hans/reference/predicate/isNotNil' },
@@ -173,7 +174,7 @@ function sidebar(): DefaultTheme.Sidebar {
             { text: 'startsWith (兼容性)', link: '/zh_hans/reference/string/startsWith' },
             { text: 'endsWith (兼容性)', link: '/zh_hans/reference/string/endsWith' },
           ],
-        }
+        },
       ],
     },
   ];

docs/reference/predicate/isLength.md

@@ -2,7 +2,7 @@
 
 Checks if a given value is a valid length.
 
-This function tests whether the provided value is of type `number`, is a non-negative integer, and is less than or equal to JavaScript's maximum safe integer (`Number.MAX_SAFE_INTEGER`). It returns `true` if the value is a valid length, and `false` otherwise.
+A valid length is of type `number`, is a non-negative integer, and is less than or equal to JavaScript's maximum safe integer (`Number.MAX_SAFE_INTEGER`). It returns `true` if the value is a valid length, and `false` otherwise.
 
 This function can also serve as a type predicate in TypeScript, narrowing the type of the argument to a valid length (`number`).
 

docs/zh_hans/reference/predicate/isLength.md

@@ -0,0 +1,41 @@
+# isLength
+
+检查给定的值是否是一个有效的长度。
+
+该函数测试提供的值是否为 `number` 类型，是非负整数，并且小于或等于 JavaScript 的最大安全整数 (`Number.MAX_SAFE_INTEGER`)。如果该值是一个有效的长度，则返回 `true`，否则返回 `false`。
+
+此函数还可以作为 TypeScript 中的类型预测器，将参数的类型缩小为有效的长度 (`number`)。
+
+## 签名
+
+```typescript
+function isLength(value: unknown): value is number;
+```
+
+### 参数
+
+- `value` (`unknown`): 要检查是否为有效长度的值。
+
+### 返回值
+
+(`value is number`): 如果值是有效长度，则返回 `true`，否则返回 `false`。
+
+## 示例
+
+```typescript
+import { isLength } from 'es-toolkit/predicate';
+
+const value1 = 0;
+const value2 = 42;
+const value3 = -1;
+const value4 = 1.5;
+const value5 = Number.MAX_SAFE_INTEGER;
+const value6 = Number.MAX_SAFE_INTEGER + 1;
+
+console.log(isLength(value1)); // true
+console.log(isLength(value2)); // true
+console.log(isLength(value3)); // false
+console.log(isLength(value4)); // false
+console.log(isLength(value5)); // true
+console.log(isLength(value6)); // false
+```