我已经根据Scott的回答编写了一个指令。你会这样使用它：
<button class="btn btn-success"
download-response="getData()"
download-success="getDataSuccess()"
download-error="getDataError()"
download-name="{{name}}.pdf"
download-backup-url="/Backup/File.pdf">
Save
</button>
问题：下面的代码在第一个方法的IE11中抛出错误TypeError: Invalid calling object（行：saveBlob(blob, filename);）。尽管它可以追溯到其他下载方法，但我的理解是saveMethod1应该在IE11中工作。
这是代码：
'use strict';
// directive allows to provide a function to be executed to get data to be downloaded
// attributes:
// download-response - Required. Function to get data. It must return a promise. It must be declared on the $scope.
// download-success - Optional. Function to be executed if download-response function was successfully resolved. It must be declared on the $scope.
// download-error - Optional. Function to be executed if download-response function return a promise rejection. It must be declared on the $scope.
// download-mime - Optional. provide a mime type of data being downloaded. Defaulted to "application/octet-stream"
// download-name - Optional. name of the file to download. Defaulted to "download.bin"
// download-backup-url - in case browser does not support dynamic download, this url will be called to get the file
angular.module('app.directives')
.directive('downloadResponse', [ '$parse', '$timeout',
function ($parse, $timeout) {
function saveMethod1(data, filename, contentType) {
// Support for saveBlob method (Currently only implemented in Internet Explorer as msSaveBlob, other extension in case of future adoption)
var saveBlob = navigator.msSaveBlob || navigator.webkitSaveBlob || navigator.mozSaveBlob || navigator.saveBlob;
if (saveBlob) {
// Save blob is supported, so get the blob as it's contentType and call save.
var blob = new Blob([data], { type: contentType });
saveBlob(blob, filename);
//console.log("SaveBlob Success");
} else {
throw 'saveBlob is not supported. Falling back to the next method';
}
}
function saveMethod2(data, filename, contentType, octetStreamMime) {
// Get the blob url creator
var urlCreator = window.URL || window.webkitURL || window.mozURL || window.msURL;
if (urlCreator) {
// Try to use a download link
var link = document.createElement("a");
var url;
if ("download" in link) {
// Prepare a blob URL
var blob = new Blob([data], { type: contentType });
url = urlCreator.createObjectURL(blob);
link.setAttribute("href", url);
// Set the download attribute (Supported in Chrome 14+ / Firefox 20+)
link.setAttribute("download", filename);
// Simulate clicking the download link
var event = document.createEvent('MouseEvents');
event.initMouseEvent('click', true, true, window, 1, 0, 0, 0, 0, false, false, false, false, 0, null);
link.dispatchEvent(event);
//console.log("Download link Success");
} else {
// Prepare a blob URL
// Use application/octet-stream when using window.location to force download
var blob = new Blob([data], { type: octetStreamMime });
url = urlCreator.createObjectURL(blob);
window.location = url;
//console.log("window.location Success");
}
} else {
throw 'UrlCreator not supported. Falling back to the next method';
}
}
function saveMethod3(attrs) {
if (attrs.downloadBackupUrl && attrs.downloadBackupUrl != '') {
console.log('opening ' + attrs.downloadBackupUrl);
window.open('http://' + document.domain + attrs.downloadBackupUrl, '_blank');
} else {
throw 'Could not download a file using any of the available methods. Also you did not provide a backup download link. No more bullets left...';
}
}
return {
restrict: 'A',
scope: false,
link:function (scope, elm, attrs) {
var getDataHandler = $parse(attrs.downloadResponse);
elm.on('click', function() {
var promise = getDataHandler(scope);
promise.then(
function (data) {
if (attrs.downloadSuccess && attrs.downloadSuccess != '') {
var successHandler = $parse(attrs.downloadSuccess);
successHandler(scope);
}
var octetStreamMime = "application/octet-stream";
var filename = attrs.downloadName || "download.bin";
var contentType = attrs.downloadMime || octetStreamMime;
try {
saveMethod1(data, filename, contentType);
return;
} catch (e) {
console.log(e);
try {
saveMethod2(data, filename, contentType, octetStreamMime);
return;
} catch (e) {
console.log(e);
try {
saveMethod3(attrs);
return;
} catch (e) {
throw e;
}
throw e;
}
throw e;
}
},
function(data) {
if (attrs.downloadError && attrs.downloadError != '') {
var errorHandler = $parse(attrs.downloadError);
errorHandler(scope);
}
}
);
});
}
};
}
]);
非常感谢您的帮助！
问题：
我已经解决了这个问题。Internet Explorer 11似乎不喜欢msSaveBlob函数的别名，最简单的例子就是：
// Succeeds
navigator.msSaveBlob(new Blob(["Hello World"]), "test.txt");
// Fails with "Invalid calling object"
var saveBlob = navigator.msSaveBlob;
saveBlob(new Blob(["Hello World"]), "test.txt");
因此，本质上，为封装saveBlob功能而创建的通用别名（这应该是允许的）阻止了msSaveBlob按预期工作：
var saveBlob = navigator.msSaveBlob || navigator.webkitSaveBlob || navigator.mozSaveBlob || navigator.saveBlob;
解决方法：
因此，我们的工作是分别对msSaveBlob进行测试。
if(navigator.msSaveBlob)
navigator.msSaveBlob(blob, filename);
else {
// Try using other saveBlob implementations, if available
var saveBlob = navigator.webkitSaveBlob || navigator.mozSaveBlob || navigator.saveBlob;
if(saveBlob === undefined) throw "Not supported";
saveBlob(blob, filename);
}
tl；dr
所以msSaveBlob方法是有效的，只要你不别名函数。也许这是一种安全预防措施-，但也许安全异常会更合适，尽管考虑到来源，我认为这很可能是一个缺陷。：）