如何检查变量是否是ES6类声明？ [英] How to check if a variable is an ES6 class declaration?

问题描述

我从一个模块导出以下ES6类：

 导出类Thingy {
 hello 
 console.log（A）; 
} 
 
 world（）{
 console.log（B）; 
} 
} 
  

并从另一个模块导入：

  importThingyfromthingy; 
 
 if（isClass（Thingy））{
 // Do something ... 
} 
  

如何检查变量是否是类？不是类实例，而是类声明？

换句话说，

在上面的例子中，c $ c> isClass 类，当代码运行时，你只有一个构造函数，或一个对象。所以你可以做

  if（typeof Thingy ==='function'）{
 //这是一个函数，所以它绝对不能是一个实例。 
} else {
 //它可以是除了构造函数之外的任何东西
} 
  

只要你知道事物是一个实例或一个构造函数。

I am exporting the following ES6 class from one module:

export class Thingy {
  hello() {
    console.log("A");
  }

  world() {
    console.log("B");
  }
}

And importing it from another module:

import {Thingy} from "thingy";

if (isClass(Thingy)) {
  // Do something...
}

How can I check whether a variable is a class? Not a class instance, but a class declaration?

In other words, how would I implement the isClass function in the example above?

解决方案

In ES6, there is no "class" when code is running, you just have a constructor function, or an object. So you could do

if (typeof Thingy === 'function'){
  // It's a function, so it definitely can't be an instance.
} else {
  // It could be anything other than a constructor
}

As long as you know for a fact that something is either an instance or a constructor.

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