TypeScript - 如何在异步方法中访问 "this"

Question

我有这段代码:

export class Profile {

    private resource: Resource = new Resource();


    /**
     * Problem here
     */
    async initialize(): Promise<void> {
        console.log(this.resource);

        var html = await this.resource.fetch(true);

        const $profile = jQuery(html);

        console.log($profile.find("span.largetext"));


    }
}

如果你能看到 console.log(this.resource) 这行，我得到了未定义。异步方法不能访问“this”吗？

我还使用 console.log(this) 进行了测试，它在网络检查器中返回了 Profile { }。

有什么方法可以访问 this 吗？

Answer 1

class Profile {

    private resource: number = 1;


    /**
     * Problem here
     */
    async initialize(): Promise<void> {
        console.log(this.resource);
    }
}


let p = new Profile();
p.initialize();


let p = new Profile();
p.initialize();

我创建了这个转换为的示例脚本

var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promise, generator) {
    return new Promise(function (resolve, reject) {
        generator = generator.call(thisArg, _arguments);
        function cast(value) { return value instanceof Promise && value.constructor === Promise ? value : new Promise(function (resolve) { resolve(value); }); }
        function onfulfill(value) { try { step("next", value); } catch (e) { reject(e); } }
        function onreject(value) { try { step("throw", value); } catch (e) { reject(e); } }
        function step(verb, value) {
            var result = generator[verb](value);
            result.done ? resolve(result.value) : cast(result.value).then(onfulfill, onreject);
        }
        step("next", void 0);
    });
};
class Profile {
    constructor() {
        this.resource = 1;
    }
    /**
     * Problem here
     */
    initialize() {
        return __awaiter(this, void 0, Promise, function* () {
            console.log(this.resource);
        });
    }
}
let p = new Profile();
p.initialize();
//# sourceMappingURL=main.js.map

输出是

1

如预期。所以结论是，它与 this 关键字无关。我猜是关于 Resource 类。