Default Value clearing and value assignment methods for input file

Most of the 1st methods are traditional, replacing html CodeThe upstairs has been used. I just optimized it with regular expressions;
2nd methods use sendkeys to simulate keyboard operations. You must allow the browser to call ActiveX;
The 3rd method is a bit like "Qian Kun" in martial arts novels! <Input type = "file" value = "C: \ abc.txt"> </P> <p> <button onclick = "clearmethod1 ();"> clear method 1: li daitao </button> <br/> <button onclick = "clearmethod2 ();"> clear Method 2: </button> </P> <p> <input type = "text" value = ""> <input type = "file" value = "C: \ abc.txt "onchange =" this. previussibling. value = This. value; "style =" width: 20 "> </P> <p> <button onclick =" clearmethod3 (); "> clear method 3: sound east to west </button> <br/>