bluebird Promise 链此参考

Question

我正在努力使用具有多种功能的 class。他们每个人 return 都是一个承诺。

我的问题是，在 Promise 的第一个 return 之后，下一个函数中的 this-reference 不是 class 对象而是全局节点对象。

下面是一些示例代码：

index.js:

"use strict";

const debug = require("./dbg.js");
const testClass = require("./testClass.js");


const dbg = new debug();

const tc = new testClass(dbg);


tc.printTestMessage()
    .then(tc.Test1)
    .then(tc.Test2)
    .then(tc.Test3);

testClass.js:

"use strict";


const Promise = require("bluebird");

let testClass = function(dbg) {

let self = this;

self._dbg = dbg;



};

testClass.prototype.printTestMessage = function() {

    let self = this;

    return new Promise(function(resolve) {

        self._dbg.printDebug(3, "testClass - printTestMessage", "start printing...");

        setTimeout(function() {

            self._dbg.printDebug(3, "testClass - printTestMessage", "finished printing...");
        resolve();

        }, 2000);

    });

};


testClass.prototype.Test1 = function() {

    let self = this;

    return new Promise(function(resolve) {

        self._dbg.printDebug(3, "testClass - Test1", "start printing...");

        setTimeout(function() {

            self._dbg.printDebug(3, "testClass - Test1", "finished printing...");
            resolve();

        }, 2000);

    });

};


testClass.prototype.Test2 = function() {

    let self = this;

    return new Promise(function(resolve) {

        self._dbg.printDebug(3, "testClass - Test2", "start printing...");

       setTimeout(function() {

            self._dbg.printDebug(3, "testClass - Test2", "finished printing...");
            resolve();

        }, 2000);

    });

};


testClass.prototype.Test3 = function() {

    let self = this;

    return new Promise(function(resolve) {

        self._dbg.printDebug(3, "testClass - Test3", "start printing...");

        setTimeout(function() {

            self._dbg.printDebug(3, "testClass - Test3", "finished printing...");
            resolve();

        }, 2000);

    });

};




module.exports = testClass;

关于如何将每个函数坚持到 class 参考的任何帮助？

Answer 1

自己找的：每一个新的Promise都要在末尾加上.bind(self)

例如：

testClass.prototype.Test3 = function() {

    let self = this;

    return new Promise(function(resolve) {

        self._dbg.printDebug(3, "testClass - Test3", "start printing...");

        setTimeout(function() {

            self._dbg.printDebug(3, "testClass - Test3", "finished printing...");
            resolve();

        }, 2000);

    }).bind(self); //<-- this is the important part

};

bluebird Promise 链此参考

bluebird Promise chain this reference

javascript

node.js

promise

bluebird