javascript实现上传文件到后台接收

	<input type="file" name="upload_img" id='upload_img'/>
	<img src="" id='myfile_img' alt='' title='' width='300'/> 
	<script type="text/javascript">
	
	var uploadImg = document.getElementById('upload_img');
	var myfileImg = document.getElementById('myfile_img');

	uploadImg.onchange = function()
	{
		var imgName = this.files[0].name;
		//let reader = new FileReader();
		var fordata = new FormData();
		fordata.append('my_file',this.files[0]);
		
		//向服务器发送文件数据
		ajaxPost(fordata,function(obj){

			var content = JSON.parse(obj.response);
			console.log(content);
			if(content.status == 'sucess'){
				myfileImg.src = './images/'+imgName;
			}
		});

	}

	function ajaxPost(data,fn)
	{
		var xhr = new XMLHttpRequest();
		xhr.open('post','./upload.php','true');
		xhr.send(data);
		xhr.onload = function()
		{
			fn(this);
		} 
	}
	</script>

$success = array('status' => 'sucess', 'code' => '1');
$error = array('status' => 'error', 'code' => '0');

if (!empty($_FILES)) {
    $file = $_FILES['my_file'];

    $new_file_dir = dirname(__FILE__) . '/images/' . $file['name'];
    @move_uploaded_file($file['tmp_name'], $new_file_dir);

    exit(json_encode($success));
} else {
    exit(json_encode($error));
}