未捕获的TypeError：使用窗口时不是函数[functionName]

I found this page here about calling a function from a string. At the bottom there's an update that states it's better to use window[functionName](params), and gives this example:

我在这里找到了关于从字符串调用函数的页面。在底部有一个更新，声明最好使用window [functionName]（params），并给出了这个例子：

var strFun = "someFunction";
var strParam = "this is the parameter";

//Create the function
var fn = window[strFun];

//Call the function
fn(strParam);

So, I wrote this:

所以，我写了这个：

  var OnChange = function( e )
  {
    var oContainer = _.DOM.GetElementByAttribute( document, 'data-instance', _testInstance );

    var evt = ( e ) ? e : window.event;
    var objects = GetObjects( oContainer );
    var files = [];

    if( evt.target.files ) // html5 .. multiple?
    {
      for( var i = 0; i < evt.target.files.length; i++ )
        files.push( evt.target.files[i].name ); //  + " (" + Format.Size( evt.target.files[i].size ) + ")" );
    }
    else
    {
      files.push( evt.target.value );
    }

    var strFunc = "User.UploadPicture";
    var test = window[strFunc];
    test(e); // error
  };

And I'm getting the following error:

而且我收到以下错误：

Uncaught TypeError: test is not a function

未捕获的TypeError：test不是函数

User.Upload is a function inside the js file. Am I missing something?

User.Upload是js文件中的一个函数。我错过了什么吗？

1 个解决方案

#1

Assuming that User is a globally scoped object containing a function UploadPicture, you would need to call it like this:

假设User是一个包含函数UploadPicture的全局范围对象，您需要像这样调用它：

var test = window["User"]["UploadPicture"];
test(e);

window["User.UploadPicture"] refers to a property called, literally, "User.UploadPicture" on the window object, and is nothing to do with the User object.

window [“User.UploadPicture”]是指在窗口对象上称为“User.UploadPicture”的属性，与User对象无关。

In this instance however, the page you've linked to seems to be talking about calling a function that you'll determine the name of at runtime. If, in your case, you're always going to call User.UploadPicture, there's nothing wrong with calling it directly:

但是，在这种情况下，您链接到的页面似乎在讨论调用一个函数，您将在运行时确定其名称。在你的情况下，如果你总是要调用User.UploadPicture，那么直接调用它是没有错的：

User.UploadPicture(e);

You only need to use the other methods if you don't know the name when you're writing the code, and instead want to dynamically invoke different functions at runtime.

如果在编写代码时不知道名称，则只需要使用其他方法，而是希望在运行时动态调用不同的函数。

#1