TypeError: Date is not a constructor

问题

So, I've been making forms for my company for some time now with pretty easy Javascript that has worked for me in the past. However all of a sudden it's kicking out the error: TypeError: Date is not a constructor

The Code:

var Date = this.getField("Text1");
Date.value = util.printd("mm/dd/yyyy",new Date());

It works on all my old forms, but now it won't work on new ones... and I've tried making a new button on an old form - just copying and pasting the code, and then it'll break all the other buttons and spit out the same error.

Running: Windows 7 64-bit with Acrobat XI 11.0.10

回答1:

The variable Date is hiding the global function Date and causing this error. Because of how scoping works in JS, the inner-most use of a name is the one that matters.

In this case, you declare var Date which becomes the only Date the function knows about. When you assign it a field or text (Date = this.getField...), you hide the global class.

You can rename your variable (I would suggest date, as capital names are typically reserved for types) or explicitly reference new window.Date when you go to construct a new date.

回答2:

This worked for me:

  var d = new window.Date();

回答3:

You can't define a variable called "Date" because there's a built-in object in JS called that (you're using it in your code, actually). Change the name to something else.

var Date= somthing; <-- wrong declare, you should not use build -in object name

回答4:

I was having this problem and I solved it! don't use "Date" as variable because this causes conflict with Global function Date();

Exemple: Wrong !

var Date = new Date();
     document.getElementById('dateCopy').innerHTML = Date.getFullYear();

Right:

var DateTime = new Date();
      document.getElementById('dateCopy').innerHTML = DateTime.getFullYear();

In your case:

var DateTime = this.getField("Text1");
DateTime.value = util.printd("mm/dd/yyyy",new Date());

来源：https://stackoverflow.com/questions/30130241/typeerror-date-is-not-a-constructor