摘自：https://github.com/henryluki/FormData/blob/master/formdata.js
if(!window.FormData) {
(function(self) {
var BOUNDARY, BlobPart, CRLF, FormData, StringPart, support;
if (self.FormData) {
return;
}
support = {
arrayBuffer : !!self.ArrayBuffer,
blob : !!self.FileReader && !!self.Blob && (function() {
try {
new Blob();
return true;
} catch (_error) {
return false;
}
})()
};
CRLF = "\r\n";
BOUNDARY = "--------FormData" + Math.random();
StringPart = (function() {
function StringPart(name, value) {
this.name = name;
this.value = value;
}
StringPart.prototype.convertToString = function() {
var lines;
lines = [];
return new Promise((function(_this) {
return function(resolve) {
lines.push("--" + BOUNDARY + CRLF);
lines.push("Content-Disposition: form-data; name=\""
+ _this.name + "\";" + CRLF + CRLF);
lines.push("" + _this.value + CRLF);
return resolve(lines.join(''));
};
})(this));
};
return StringPart;
})();
BlobPart = (function() {
function BlobPart(name, filename, souce) {
this.name = name;
this.filename = filename;
this.souce = souce;
}
BlobPart.prototype._readArrayBufferAsString = function(buff) {
var view;
view = new Uint8Array(buff);
return view.reduce(function(acc, b) {
acc.push(String.fromCharCode(b));
return acc;
}, new Array(view.length)).join('');
};
BlobPart.prototype._readBlobAsArrayBuffer = function() {
return new Promise((function(_this) {
return function(resolve) {
var reader;
reader = new FileReader();
reader.readAsArrayBuffer(_this.souce);
return reader.onload = function() {
return resolve(_this
._readArrayBufferAsString(reader.result));
};
};
})(this));
};
BlobPart.prototype._readBlobAsBinary = function() {
return new Promise((function(_this) {
return function(resolve) {
return resolve(_this.souce.getAsBinary());
};
})(this));
};
BlobPart.prototype.convertToString = function() {
var lines;
lines = [];
lines.push("--" + BOUNDARY + CRLF);
lines.push("Content-Disposition: form-data; name=\"" + this.name
+ "\"; filename=\"" + this.filename + "\"" + CRLF);
lines.push("Content-Type: " + this.souce.type + CRLF + CRLF);
if (support.blob && support.arrayBuffer) {
return this._readBlobAsArrayBuffer().then(function(strings) {
lines.push(strings + CRLF);
return lines.join('');
});
} else {
return this._readBlobAsBinary().then(function(strings) {
lines.push(strings + CRLF);
return lines.join('');
});
}
};
return BlobPart;
})();
FormData = (function() {
function FormData() {
this.polyfill = true;
this._parts = [];
this.boundary = BOUNDARY;
}
FormData.prototype._stringToTypedArray = function(string) {
var bytes;
bytes = Array.prototype.map.call(string, function(s) {
return s.charCodeAt(0);
});
return new Uint8Array(bytes);
};
FormData.prototype.append = function(key, value) {
var part;
part = null;
if (typeof value === "string") {
part = new StringPart(key, value);
} else if (value instanceof Blob) {
part = new BlobPart(key, value.name || "blob", value);
} else {
part = new StringPart(key, value);
}
if (part) {
this._parts.push(part);
}
return this;
};
FormData.prototype.toString = function() {
var parts;
parts = this._parts;
return Promise.all(this._parts.map(function(part) {
return part.convertToString();
})).then(function(lines) {
lines.push("--" + BOUNDARY + "--");
return lines.join('');
}).then(this._stringToTypedArray);
};
return FormData;
})();
return self.FormData = FormData;
})(typeof self !== 'undefined' ? self : this);
}DWR异步上传的核心原理：
// 复制替身
var clone = value.cloneNode(true);
// 移除自身ID
value.removeAttribute("id", prop);
// 设置自身名称
value.setAttribute("name", prop);
// 隐藏自身
value.style.display = "none";
// 插入替身
value.parentNode.insertBefore(clone, value);
// 移除自身
value.parentNode.removeChild(value);
// 加进iframe里的form中
batch.form.appendChild(value);