文件上传

<input type="file" id="id-input-file-3">

FormData，用来上传文件很好用。

var file = jQuery('#fileid').get(0).files[0]; // 得到文件
var formData = new FormData(); // 新建一个FormData对象
formData.append('file', file); //
formData.append('uid', 123); // 向FormData对象添加字段
$.ajax({
url:'/admin/ajax/fileuploadTmp',
type:'POST',
data: formData,
success: function(data, status) {
console.log(data);
},
processData: false,  // tell jQuery not to process the data
contentType: false   // tell jQuery not to set contentType
});

var oOutput = document.getElementById("output")]var oData = new FormData(document.forms.namedItem("fileinfo"));

oData.append("CustomField", "This is some extra data");

var oReq = new XMLHttpRequest();
oReq.open("POST", "stash.php", true);
oReq.onload = function(oEvent) {
if (oReq.status == 200) {
oOutput.innerHTML = "Uploaded!";
} else {
oOutput.innerHTML = "Error " + oReq.status + " occurred uploading your file.<br \/>";
}
};

oReq.send(oData);

FormData - Web API 接口| MDN

使用FormData对象- Web 开发者指南| MDN