Method to make an input text box change the length according to the content_HTML/Xhtml_Web page production

First:

Copy code

The code is as follows:

The size="4" is to define the initial size. If it is not defined here, then change the 4 in this.size=(this.value.length>4?this.value.length:4); into 20, the default size of is 20

Second:
If you define the width attribute in the style, let its width change according to the content , aren’t the two requirements contradictory? So the width attribute cannot be defined in style here.