子字符串将仅返回该子字符串，而不会在文本框中突出显示该单词

AFAIK，您不能在asp:TextBox控件中执行此操作.
您将需要使用 ^ ].

我使用了 http://freetextbox.com/ [ ^ ]有时回到我的示例项目之一.这也将满足您的要求.看一看. :thumbsup:

The Substring will just return that Substring this wont highlight that word in a Textbox

AFAIK, you can''t do this in asp:TextBox control.
You will need to use RichTextBox[^].

I used http://freetextbox.com/[^] sometime back in one of my sample project. This will also do what you require. Take a look. :thumbsup:

document.getElementById(''ASP_CONTROL_ID_HERE'').select();