使用ajaxcontroltoolkit TextBoxWatermark时使用javascript检查文本框是否为空

Question

I have an asp.net TextBox and I'm using the TextBoxWatermark of AjaxControlToolkit to have it display some hing text while the box is empty.

Problem is, onclient click of a certain button, I want to determine if the textbox is empty. The javascript code of

document.getElementById(fieldName).value == ""

Is not working, since the WaterMark extender with it's hint text making the code to think the field is not empty.

Any solution to this?

Answer 1

You can use the wrapper to access whether the watermark is being displayed or not with get_IsWaterMarked .

Sys.Extended.UI.TextBoxWrapper.get_Wrapper(document.getElementById(fieldName)).get_IsWatermarked()

I tried this with version 4.1.7.1213 of AjaxControlToolKit.

Got the code from looking at the source code of the TextBoxWatermark control. Refer to this: http://ajaxcontroltoolkit.codeplex.com/SourceControl/latest#Client/MicrosoftAjax.Extended/TextboxWatermark/TextboxWatermark.pre.js