如何在一个promise数组中引用一个对象值？

Question

The Object below contains lookup keys which contain an Array of Promises used to run a series of validations against a value .

How can the value of full_name be accessible from email ?

const config = {
  full_name: [
    val => new Promise((resolve, reject) => resolve(val)),
    val => new Promise((resolve, reject) => resolve(val))
  ],
  email: [
    val => new Promise((resolve, reject) => resolve(val)),
    val => new Promise((resolve, reject) => reject(`${config.full_name.val}`)) // get the value which has been passed to full_name
  ]
}

Answer 1

config.full_name.val does not exist, because config.full_name is an array with functions that return promises.

The use case here depends on the context of how these functions are invoked. This context is explained here: https://jsfiddle.net/karlbateman/keqnrybq/ .

Considering also that the validation part lives in a different module than the actual config, one cannot simply access the formData in the callbacks.

However, you can add a context param to your function callbacks which provides the formData to be accessed, as shown here: https://jsfiddle.net/odolha/tpn75570/

See this line (in the validatorFn):

arr.push(config[field].map(cb => cb(formData[field], formData)))

This basically provides the formData as a context param, which can be used later:

(val, ctx) => new Promise((resolve, reject) => setTimeout(() => {
  reject(`${ctx.name} already is exists.`) // simulate a HTTP request
}, 2000))

Answer 2

You may also implement a similar functionality as follows;

 function promisifier(val, pass = true){ return new Promise(function(v,x){ return pass ? v(val) : x(val); }); } var config = { full_name: [promisifier, promisifier], email: [promisifier, promisifier] }; config.full_name[0]("Thaddeus Jones") .then(r => config.email[1](r,false)) .then(r => console.log("resolved by:", r)) .catch(e => console.log("received error:", e));