html
<input type="file" id="coverPhoto-file" onchange="submit()">
js
function submit() {
var formData = new FormData();
var file = document.getElementById("coverPhoto-file").files[0];
formData.append("photo", file);
$.ajax({
url:"url地址",
type:"POST",
data:formData,
processData : false,
contentType : false,
dataType : 'json',
async : false,
success : function (result) {
//成功后的回调事件
}
})
}