如何防止警告'属性MyProp1从未在MyObject上定义'？ [英] How can I prevent the warning 'Property MyProp1 never defined on MyObject'?

问题描述

我有一些包含JSON字符串的HTML。在 on DOM ready 回调中，我有类似这样的内容：

I have some HTML that contains a JSON string. In the on DOM ready callback, I have something like this:

MyObject = JSON.parse($('#TheJsonString').html());

稍后在我的代码中，我写了一些内容：

Later in my code, I write something this:

var SomeVar = MyObject.MyProp1;

然后当我通过Google闭包编译器运行代码时，我收到警告

And then when I run the code through the Google closure compiler, I get the warning

属性MyProp1从未在MyObject上定义。

Property MyProp1 never defined on MyObject.

应该如何编写代码，以便它不会产生警告？

How should the code be written so that it doesn't generate a warning?

推荐答案

删除警告的最简洁方法是定义JSON的结构。这可以使用 @来完成键入 标记：

The cleanest way to remove the warning is by defining the structure of the JSON. This can be done using the @type tag:

/** @type {{MyProp1:string}} */

其中 MyProp1 是属性和字符串是类型。

Google的Closure编译器将重命名该变量。如果你不想这样，你必须使用引号+括号而不是点符号：

Google's Closure compiler will rename the variable. If you don't want that, you have to use quotes + brackets instead of the dot-notation:

MyObject['MyProp1']

示例：将以下内容粘贴到关闭编译器：

Example: paste the following in the Closure Compiler:

// ==ClosureCompiler==
// @compilation_level ADVANCED_OPTIMIZATIONS
// ==/ClosureCompiler==

var MyObject;
function x() { // Magic happens at the next line
    /** @type {{MyProp1:string}}*/
    MyObject = JSON.parse(prompt(''));
}
function afterX() {
    var SomeVar = MyObject.MyProp1;
    alert(SomeVar);
}
x();
afterX();

输出：

var a;a=JSON.parse(prompt(""));alert(a.a);

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