近期在學習typescript的時候，發現ts居然可以對原生js做強檢測。發現從v2.3就開始直接了。這讓我感嘆他的變化，又讓我自己感到學習的緩慢。本文章就對他小試牛刀一下。
一、他是的使用與支持
通過閱讀官網的說明，了解到他實現驗證是通過jsdoc的注釋結構實現。然后在.js文件頭部加入如下注釋標簽即可：
| 標記 | 說明 |
| // @ts-nocheck | 標記此文件不做類型檢測 |
| // @ts-check | 標記此文件做類型檢測，但沒有用--checkJS參數時 |
| // @ts-ignore | 標記后面一段不做類型檢測（可以說是后面一行） |
二、示例展示
簡要示例代碼如下：
// @ts-check /** * @type {number} */ var x; x="12";
效果圖如下：
是否很神奇，編譯環境能識別出類型的差異。其他測試截圖如下：
三、疑問
1. 按照官網的說明，對object對象也可以做到檢測，但測試貌似不可以，還望各位幫忙解疑（官網原話如下）:
Object literals are open-ended
By default object literals in variable declarations provide the type of a declaration. No new members can be added that were not specified in the original initialization. This rule is relaxed in a .js file; object literals have an open-ended type, allowing adding and looking up properties that were not defined originally. For instance:
var obj = { a: 1 }; obj.b = 2; // Allowed
Object literals get a default index signature [x:string]: any that allows them to be treated as open maps instead of closed objects.
Similar to other special JS checking behaviors, this behavior can be changed by specifying a JSDoc type for the variable. For example:
/** @type */ var obj = { a: 1 }; obj.b = 2; // Error, type {a: number} does not have property b