为什么是“这个"?null，在 Angular 指令中的链接函数中? [英] Why is "this" null, in the link function within an Angular Directive?

问题描述

我正在尝试使用 TypeScript 和 Angular 编写动态模板，但是由于某种原因，this"关键字始终为空，因此我无法访问我的私有成员 $compile.有任何想法吗?非常感谢！:-)

I'm trying to write a dynamic template using TypeScript and Angular, however for some reason the 'this' keyword is always null, thus I cannot access my private member $compile. Any ideas? Many Thanks! :-)

指令:

namespace ROD.Features.Player {
    "use strict";

    export class VideoDirective implements ng.IDirective {
        public restrict: string = "E";
        public replace: boolean = true;
        public scope = {
            content: "="
        };

        constructor(private $compile: ng.ICompileService) {
        }

        public link(element: JQuery, scope: ng.IScope): any {
            const youtubeTemplate = "<p>Youtube</p>";
            const vimeoTemplate = "<p>Vimeo</p>";

            var linkFn = this.$compile(youtubeTemplate);
            const content: any = linkFn(scope);
            element.append(content);
        }
    }
}

App.ts:

namespace ROD {
    "use strict";
    angular.module("rodApp", [])
        .service("Settings", [() => new Settings.DevelopmentSettings()])
        .service("RedditService", [
            "$http", "Settings",
            ($http: ng.IHttpService, settings: Settings.ISettings) => new Services.Reddit.RedditService($http, settings.sourceUrl),
        ])
        .directive("videoItem", ["$compile",
            ($compile: ng.ICompileService) => new Features.Player.VideoDirective($compile)])
        .controller("PlayerController", [
            "$scope", "RedditService",
            ($scope: any, redditService: Services.Reddit.IRedditService) => new Features.Player.PlayerController($scope, redditService),
        ]);
}

推荐答案

看来我对链接函数使用了错误的语法.这是正确的实现:

It appears that I was using the wrong syntax for the link function. This is the correct implementation:

        public link = (element: JQuery, scope: ng.IScope): any => {
            const youtubeTemplate = "<p>Youtube</p>";
            const vimeoTemplate = "<p>Vimeo</p>";

            var linkFn = this.$compile(youtubeTemplate);
            const content: any = linkFn(scope);
            element.append(content);
        }

谁能解释一下这是为什么?:-)

Can anyone explain why this is? :-)

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