Jquery focus () cannot get focus

One small problem today is that the text box can be submitted only after you enter the content. If you do not enter the content, a prompt will be prompted and the text box will get the focus! If jquery is not used, is it an object. focus () is enough, but when we use jquery, $ ("# nameinput") returns a jquery object instead of a DOM object, in this case, $ ("# nameinput "). the significance of the Focus () method has changed. Instead of getting the focus of this text box, it triggers all the functions bound to this text box in onfocus! In fact, using jquery is also very simple to convert jquery objects into a DOM object. I believe that developers have long considered this. It is really a worry for the world. $ ("# nameinput ") [0]. focus () simply adding a [0] is what we want !!