var upfile = document.getElementById("upfile"),

    opacity1 = document.getElementById("opacity1"),

    opacity0 = document.getElementById("opacity0");

​

opacity0.onclick = function() {

    upfile.style.opacity = "0";

};

​

opacity1.onclick = function() {

    upfile.style.opacity = "1";

};

​

upfile.onchange = function() {

    updateFilename(this.value);

};

​

function extractFilename(path) {

  var x;

  x = path.lastIndexOf('\\');

  if (x >= 0) // 基于Windows的路径

    return path.substr(x+1);

  x = path.lastIndexOf('/');

  if (x >= 0) // 基于Unix的路径

    return path.substr(x+1);

  return path; // 仅包含文件名

}

 function updateFilename(path) {

   var name = extractFilename(path);

   document.getElementById('filename').textContent = name;

 };

​