Bluebird：运行承诺返回函数序列

Question

运行动态生成函数序列的最简洁方法是什么，其中每个函数 returns 一个必须在下一个运行之前解决的 Promise？

例如：

// Assume the following 'process' functions are generated elsewhere

function process_1 (input) {
    return new Promise(function (resolve, reject) {
        resolve(input + '_1');
    });
}

function process_2 (input) {
    return new Promise(function (resolve, reject) {
        resolve(input + '_2');
    });
}

function process_3 (input) {
    return new Promise(function (resolve, reject) {
        resolve(input + '_3');
    });
}

// We can construct a sequence of these functions,
// but each one still needs to be 'configured' with a value
// before it can return it's promise.

var process = [process_1, process_2, process_3]

Bluebirds Promise 上可用的收集方法（例如 all、each 等）似乎处理值的集合，而不是比承诺生成函数的集合。

如果我尝试将序列映射或缩减为一系列 promise 而不是函数，那么我将失去将一个 promise 的结果传递到下一个 promise 的能力吗？

Answer 1

您可以为此使用 reduce：

bluebird.reduce( [process_1, process_2, process_3], function ( input, next ) {                                                                                                                                     
    return next( input );
}, 'INPUT' ).then( function ( result ) { 
    console.log( result );
} );

注意：您还缺少 process_2 和 process_3 的输入参数，必须添加该参数才能使其工作。

function process_1 (input) {
    return new Promise(function (resolve, reject) {
        resolve(input + '_1');
    });
}

function process_2 ( input ) {
    return new Promise(function (resolve, reject) {
        resolve(input + '_2');
    });
}

function process_3 ( input ) {
    return new Promise(function (resolve, reject) {
        resolve(input + '_3');
    });
}

bluebird.reduce( [process_1, process_2, process_3], function ( input, next ) {
    return next( input );                                                                                                                                                                                          
}, 'INPUT' ).then( function ( result ) {
    console.log( result );
} );

// INPUT_1_2_3

Answer 2

这是另一种 non-bluebird-specific 方式：

var p = arrayOfFns.reduce((p, c) => p.then(c), Promise.resolve('INPUT'));
p.then(console.log);

Bluebird：运行承诺返回函数序列

Bluebird: Run sequence of promise-returning functions

javascript

arrays

promise

bluebird

Bluebird：运行 承诺返回函数序列

Bluebird: Run sequence of promise-returning functions

javascript

arrays

promise

bluebird

Bluebird：运行承诺返回函数序列