javascript sets the focus position in the text box_javascript skills

Copy code The code is as follows:

var obj=document.getElementById("txtUserID")
var range=obj.createTextRange()
//The starting position of the selected text (starting from the 3rd character)
range.moveStart("character",3)
//The ending position of the selected text (Before the third last character of all characters)
range.moveEnd("character",-3)
//Select
range.select()