Question

我想根据案例执行一个函数，从5个函数中选择。然后获取该函数的返回值，使用它来执行一个额外的函数（每种情况都相同）

我相信所有的功能都是同步的。

var x = require('./file2.js')

export default (metadata) => {
    return (req, next) => {
      var fn = new x (req, next, metadata)
      var metric = (req.body.metric)
      var choices = {
                "1": fn.one(),
                "2": fn.one(),
                "3": fn.one(),
                "4": fn.one(),
                "5": fn.two(),
                "6": fn.three(),
                "7": fn.four(),
                "8": fn.five()
      };
var jql = choices[metric]// When I put console.log's in all the function (one through five) they all print out.

file2.js：

var x = function (req, next, metadata) {
this.req = req;
this.next = next;
this.start = metadata.body.start;
}

x.prototype.one = function (){
   var jql = ['test',
    'AND ' + this.start].join("\n")
   return jql
}
module.exports = x;

Answer 1

如果你想做我认为你想做的事，那么你需要这样的事情：

/*
 Since you want to call a method on an instance of a class, first bind them to 
 the proper scope (might want to rethink the name fn). 
 Function#bind creates a new function that executes with the proper scope
*/
const one = fn.one.bind(fn)
const two = fn.two.bind(fn)
const three = fn.three.bind(fn)
const four = fn.four.bind(fn)
const five = fn.five.bind(fn)

// Create your object of choices with these functions
const choices = {
  "1": one,
  "2": one,
  "3": one,
  "4": one,
  "5": two,
  "6": three,
  "7": four,
  "8": five
}

// Then you can use it like this:
choices['1'](/* whatever arguments it needs */)

Javascript对象文字表示法执行所有值

1 个答案: