Ajax上傳文件進(jìn)度條Codular

!doctype html>
html>
head>
  meta charset="utf-8">
  title>JS File Upload with Progress/title>
  style>
  .container {
    width: 500px;
    margin: 0 auto;
  }
  .progress_outer {
    border: 1px solid #000;
  }
  .progress {
    width: 20%;
    background: #DEDEDE;
    height: 20px; 
  }
  /style>
/head>
body>
  div class='container'>
    p>
      Select File: input type='file' id='_file'> input type='button' id='_submit' value='Upload!'>
    /p>
    div class='progress_outer'>
      div id='_progress' class='progress'>/div>
    /div>
  /div>
  script src='upload.js'>/script>
/body>
/html>

var _submit = document.getElementById('_submit'), 
_file = document.getElementById('_file'), 
_progress = document.getElementById('_progress');

_submit.addEventListener('click', upload);

if(_file.files.length === 0){
  return;
}

var data = new FormData();
data.append('SelectedFile', _file.files[0]);

var request = new XMLHttpRequest();
request.onreadystatechange = function(){
  if(request.readyState == 4){
    try {
      var resp = JSON.parse(request.response);
    } catch (e){
      var resp = {
        status: 'error',
        data: 'Unknown error occurred: [' + request.responseText + ']'
      };
    }
    console.log(resp.status + ': ' + resp.data);
  }
};

request.upload.addEventListener('progress', function(e){
  _progress.style.width = Math.ceil(e.loaded/e.total) * 100 + '%';
}, false);

request.open('POST', 'upload.php');
request.send(data);

var _submit = document.getElementById('_submit'), 
_file = document.getElementById('_file'), 
_progress = document.getElementById('_progress');
var upload = function(){
  if(_file.files.length === 0){
    return;
  }
  var data = new FormData();
  data.append('SelectedFile', _file.files[0]);
  var request = new XMLHttpRequest();
  request.onreadystatechange = function(){
    if(request.readyState == 4){
      try {
        var resp = JSON.parse(request.response);
      } catch (e){
        var resp = {
          status: 'error',
          data: 'Unknown error occurred: [' + request.responseText + ']'
        };
      }
      console.log(resp.status + ': ' + resp.data);
    }
  };
  request.upload.addEventListener('progress', function(e){
    _progress.style.width = Math.ceil(e.loaded/e.total) * 100 + '%';
  }, false);
  request.open('POST', 'upload.php');
  request.send(data);
}
_submit.addEventListener('click', upload);

?php
// Output JSON
function outputJSON($msg, $status = 'error'){
  header('Content-Type: application/json');
  die(json_encode(array(
    'data' => $msg,
    'status' => $status
  )));
}
// Check for errors
if($_FILES['SelectedFile']['error'] > 0){
  outputJSON('An error ocurred when uploading.');
}
if(!getimagesize($_FILES['SelectedFile']['tmp_name'])){
  outputJSON('Please ensure you are uploading an image.');
}
// Check filetype
if($_FILES['SelectedFile']['type'] != 'image/png'){
  outputJSON('Unsupported filetype uploaded.');
}
// Check filesize
if($_FILES['SelectedFile']['size'] > 500000){
  outputJSON('File uploaded exceeds maximum upload size.');
}
// Check if the file exists
if(file_exists('upload/' . $_FILES['SelectedFile']['name'])){
  outputJSON('File with that name already exists.');
}
// Upload file
if(!move_uploaded_file($_FILES['SelectedFile']['tmp_name'], 'upload/' . $_FILES['SelectedFile']['name'])){
  outputJSON('Error uploading file - check destination is writeable.');
}
// Success!
outputJSON('File uploaded successfully to "' . 'upload/' . $_FILES['SelectedFile']['name'] . '".', 'success');