[英]Weird behaviour with abstract method TypeScript
我在此处将打字稿与参考“ atmosphere.d.ts” 源一起使用 。 我用抽象方法触发了一个奇怪的行为,这导致了错误:
TypeError:this.protectedMethod不是函数
这是打字稿代码:
/// <reference path="../atmosphere.d.ts" />
import Request = Atmosphere.Request;
abstract class AbstractRequest {
// The atmosphere request
protected socket: Request;
// Here we initialize the socket
protected init(url: string): void {
this.socket = {
url : "http://localhost:9000/" + url,
contentType : "application/json",
transport : "websocket" ,
fallbackTransport : "long-polling"
};
/* SOME CODE */
this.socket.onOpen = function(response) {
this.protectedMethod();
};
}
// Some protected method called in this.socket.onOpen
protected abstract protectedMethod(): void;
}
class Registration extends AbstractRequest {
// Implementation of the abstract method
protected protectedMethod(): void {
console.log("hello");
}
}
没有错误,将生成以下javascript代码:
var __extends = (this && this.__extends) || function (d, b) {
for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
var AbstractRequest = (function () {
function AbstractRequest() {
}
// Here we initialize the socket
AbstractRequest.prototype.init = function (url) {
this.socket = {
url: "http://localhost:9000/" + url,
contentType: "application/json",
transport: "websocket",
fallbackTransport: "long-polling"
};
/* SOME CODE */
this.socket.onOpen = function (response) {
this.protectedMethod();
};
};
return AbstractRequest;
}());
var Registration = (function (_super) {
__extends(Registration, _super);
function Registration() {
_super.apply(this, arguments);
}
// Implementation of the abstract method
Registration.prototype.protectedMethod = function () {
console.log("hello");
};
return Registration;
}(AbstractRequest));
//# sourceMappingURL=test.js.map
实现“ onOpen”方法时,无法从“ socket”变量调用抽象方法(也可能是非抽象方法)。 我现在发现的唯一解决方法是实例化全局变量
var registration = new Registration();
接着 :
this.socket.onOpen = function(response) {
registration.protectedMethod;
};
通过这种解决方法,我必须定义“ protectedMethod”公共。 是否有对此行为的解释以及解决方法/修复程序? 顺便说一句,我使用打字稿1.8.10
谢谢,
这是由于该方式this
工作在JavaScript :
var AbstractRequest = (function () {
function AbstractRequest() { }
AbstractRequest.prototype.init = function (url) {
// ...snip...
this.socket.onOpen = function (response) {
this.protectedMethod();
};
};
return AbstractRequest;
}());
当你调用new AbstractRequest().socket.onOpen()
this
将被绑定到socket
不new AbstractRequest()
this
指向无论是在点的左边)。
您可以使用箭头功能来解决此问题。 在箭头的功能this
势必会有人在,没有它正在被运行的背景下定义的上下文:
this.socket.onOpen = response => {
this.protectedMethod();
};
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