Add the following onclick
attribute to make the entire <input>
automatically highlight when the user clicks on it:
<input type="text" value="Test1" onclick="this.select()" />
Alternatively, if you want the user to be able to change the selection after the initial click, change the onclick attribute to an onfocus
attribute. This will also highlight the entire <input>
when the user clicks on it, but it allows them to change the highlighted part manually afterwards:
<input type="text" value="Test2" onfocus="this.select()" />
Here is an example of both inputs in action.