'Promise' is undefined error when 运行 on IE

Question

我有一个控制器代码运行在 Chrome 上很好，但是当运行在 IE 10 上时，相同的代码 returns

ReferenceError: 'Promise' is undefined

returns错误的函数是：

new Promise(function(resolve) {
    MetaModel.load($scope, (regionExist ? reqParmRegion[1] : reqParmRegion), (screenExist ? reqParmScreen[1] : reqParmScreen), resolve);
}).then(function(){

    loadRelationshipByStep($scope.preStep);
     if($rootScope.regionId === 'us') {
        $rootScope.currRel = 'itself';
    } 

    if($rootScope.screenId.indexOf('search') !== -1 ){
       EnumerationService.loadEnumerationByTab();
    }  
    // load data for tab click
    if($rootScope.currRel !== 'undefined' && $rootScope.currRel !== 'itself' && $scope.regionId !== 'us'){
        $scope.loadDataByTab($rootScope.currRel);
    } else if($rootScope.resourceHref !== undefined) {
        var params = {};
         resourceFactory.get($rootScope.resourceHref, params, $rootScope.headers).success(function(responseData){
            var data = responseData.data || responseData;
            if (data) {
                $scope.data=data;
                EnumerationService.executeEnumerationFromBackEnd(data, 'create');
                if($rootScope.regionId === 'us'){
                    EnumerationService.executeEnumerationFromBackEnd(data, 'fetch');    
                }
            }
        });            
    }
});

我需要添加任何 $promise 变量吗？

Answer 1

IE 不支持原生 javascript Promise。参见 browser compatibility on MDN。

Angular 包含提供承诺功能的 $q 服务。您可以使用 $q.defer() 和 return 来自该对象的承诺创建一个延迟对象。

我认为等效代码是：

// create the deferred object
var deferred = $q.defer();

// pass the resolve method as the callback
MetaModel.load($scope, (regionExist ? reqParmRegion[1] : reqParmRegion), 
    (screenExist ? reqParmScreen[1] : reqParmScreen), deferred.resolve);

// chain actions onto the promise.
deferred.promise.then(function(){

    loadRelationshipByStep($scope.preStep);
     if($rootScope.regionId === 'us') {
        $rootScope.currRel = 'itself';
    } 

    if($rootScope.screenId.indexOf('search') !== -1 ){
       EnumerationService.loadEnumerationByTab();
    }  
    // load data for tab click
    if($rootScope.currRel !== 'undefined' && $rootScope.currRel !== 'itself' && $scope.regionId !== 'us'){
        $scope.loadDataByTab($rootScope.currRel);
    } else if($rootScope.resourceHref !== undefined) {
        var params = {};
         resourceFactory.get($rootScope.resourceHref, params, $rootScope.headers).success(function(responseData){
            var data = responseData.data || responseData;
            if (data) {
                $scope.data=data;
                EnumerationService.executeEnumerationFromBackEnd(data, 'create');
                if($rootScope.regionId === 'us'){
                    EnumerationService.executeEnumerationFromBackEnd(data, 'fetch');    
                }
            }
        });            
    }
});

Answer 2

https://github.com/stefanpenner/es6-promiseCorrect me if I'm wrong, but it seems to me that you're using the native implementation of Promise，IE 还不支持。

在这种情况下，请尝试使用 polyfill。

此外，您可以使用 Angular's $q service, which is a Promisse Pattern implementation based on kriskowal's Q module。

示例：

$q(function (resolve, reject) {
    MetaModel.load($scope, (regionExist ? reqParmRegion[1] : reqParmRegion), (screenExist ? reqParmScreen[1] : reqParmScreen), resolve);
}).then(function () {

    loadRelationshipByStep($scope.preStep);
     if($rootScope.regionId === 'us') {
        $rootScope.currRel = 'itself';
    } 

    if($rootScope.screenId.indexOf('search') !== -1 ){
       EnumerationService.loadEnumerationByTab();
    }  
    // load data for tab click
    if($rootScope.currRel !== 'undefined' && $rootScope.currRel !== 'itself' && $scope.regionId !== 'us'){
        $scope.loadDataByTab($rootScope.currRel);
    } else if($rootScope.resourceHref !== undefined) {
        var params = {};
         resourceFactory.get($rootScope.resourceHref, params, $rootScope.headers).success(function(responseData){
            var data = responseData.data || responseData;
            if (data) {
                $scope.data=data;
                EnumerationService.executeEnumerationFromBackEnd(data, 'create');
                if($rootScope.regionId === 'us'){
                    EnumerationService.executeEnumerationFromBackEnd(data, 'fetch');    
                }
            }
        });            
    }
});

Answer 3

原生 promise is an ES6 feature which is not supported by old browsers. You need to add a polyfill to support old browsers, for example https://github.com/taylorhakes/promise-polyfill.

由于您使用的是 AngularJS，因此您可以使用 $q 服务来创建跨浏览器的承诺。

'Promise' is undefined error when 运行 on IE

'Promise' is undefined error when run on IE

angularjs

angular-controller