Is input type=file placed in div with no visibility?
<form> <input id=test type=file name=test style="visibility:hidden;position:absolute;top:0;left:0" onchange="document.getElementById('info').innerHTML=this.value"> <input type=button value="get file" onclick="this.form.test.click()"> <span id="info" style="border:1px solid black"> </span> </form> 但是如果使用display: none的話，就不行，使用visibility: hidden卻可以