使用image元素也可以進行表單的提交

看下面的一段代碼，剛開始沒有弄明白原理，因爲發現下面的form表單，沒有我們平時說的input type="submit"這樣的提交按鈕，也沒有javascript中談到的form.submit綁定在某個點擊事件上面，於是卡殼了。但是的確通過圖片的提交按鈕，的確是可以對該form表單進行提交，莫非....

img也可以對錶單進行提交：

<form name="uploadForm" enctype="multipart/form-data" method="post" action="/ajax/designer_handler.php?item_id=<?=$item_id?>&tab=<?=$side?>&is_admin=<?=$is_admin?>" οnsubmit="return uploadPhoto();"  style="display:inline">
	<input type="hidden" name="MAX_FILE_SIZE" value="25000000" style="display:inline;">
	<input type="hidden" name="uploading" />
	<?php 
	$u_agent = $_SERVER['HTTP_USER_AGENT']; 
	$btnText = "Browse";
	if(preg_match('/Chrome/i',$u_agent) || preg_match('/Safari/i',$u_agent)){
		$btnText = "Choose File";
	}


	$fonts_image_path = FontsImage::getImageUrl($design_id, $side);
	//var_dump($fonts_image_path);
	?>
	Upload up to 5 files at once<br />
	Click the <?= $btnText?> buttons to select files on your computer:<br /><br />
	<table cellspacing="5">
		<tr><td height="25">Photo: <input type="file" id="pathname1" name="pathname1" style="width:300px;" accept="image/jpeg" > </td></tr>
		<tr><td height="25">Photo: <input type="file" id="pathname2" name="pathname2" style="width:300px;" accept="image/jpeg" > </td></tr>
		<tr><td height="25">Photo: <input type="file" id="pathname3" name="pathname3" style="width:300px;" accept="image/jpeg" > </td></tr>
		<tr><td height="25">Photo: <input type="file" id="pathname4" name="pathname4" style="width:300px;" accept="image/jpeg" > </td></tr>
		<tr><td height="25">Photo: <input type="file" id="pathname5" name="pathname5" style="width:300px;" accept="image/jpeg" > </td></tr>
	</table>
	<br />


	<input id="upload_button" type="image" src="/images/personalize/upload.gif" >  
    <img id="upload_button_waiting" src="/images/ajax-loader.gif" style="display:none;" /><br />
	<span id="upload_message" style="font-style:italic; color:gray; visibility:hidden">
	Uploading...  (Large pictures may take some time to upload)
	</span><br /><br />
	</form>

原來：

表單控件(Form Control)：圖片提交(input type="image")

input type=image 相當於 input type=submit，不同的是，input type=image 以一個圖片作爲表單的提交按鈕，其中 src 屬性表示圖片的路徑。