javascript中函数的替代方法

Question

I would like to know is there any alternative method for a function in my scenario in javascript

Below function works fine, but is there any alternative method to do, since there are more obj

//will get single object as response as anyof these 
obj ={"id":"trans", "cn": "SG", "ccy": "SGD"};
obj ={"id": "remit", "cn": "TH", "ccy": "THB"};
obj ={"id": "fund", "cn": "IN", "ccy": "INR"};

function getTrans(){
  var value = 1000;
  var rate = 0.5;
  return value * rate;
}

function getFund(){
  var value = 2000;
  var rate = 0.2;
  return value * rate;
}

var result = getData(obj);

function getData(obj){
 if(obj.id==="trans"){
  return  getTrans(obj);
  }
 else if(obj.id==="fund"){
  return   getFund(obj);
 }
else{
  return obj;
 }
}

Answer 1

You would usually write a map letting you access your function, for example

//will get object as response 
var obj ={"id":"trans", "cn": "SG", "ccy": "SGD"};
var obj ={"id": "remit", "cn": "TH", "ccy": "THB"};
var obj ={"id": "fund", "cn": "IN", "ccy": "INR"};

const extractors = {
    trans(obj) { 
        var value = 1000;
        var rate = 0.5;
        return value * rate;// this should probably use obj
    },
    fund(obj) {
        var value = 2000;
        var rate = 0.2;
        return value * rate;
    }
}

function getData(obj){
    let extractor = extractors[obj.id];
    return extractor ? extractor(obj) : obj;
}

var result = getData(obj);

If you have other similar functions to associate to your ids, you could use objects instead of functions:

const handlers = {
     trans: {
           getData: obj => ...,
           foo: obj => ...
     },
     ...

and then access the functions with

 function getData(obj){
     let handler = handlers[obj.id];
     return handler ? handler.getData(obj) : obj;
 }

This kind of pattern is very extensible and is suited to injections, meaning you can have a global getData code not aware of the various types, but other parts of your applications registering new handlers.

Answer 2

 class ObjX{ constructor(id,cn,ccy){ this.id=id; this.cn=cn; this.ccy=ccy; } trans=function(){ var value = 1000; var rate = 0.5; return value * rate; } fund=function(){ var value = 2000; var rate = 0.2; return value * rate; } getData(){ if(this[this.id]){ return this[this.id](); }else{ return this; } } } obj =new ObjX("trans","SG","SGD"); obj2 =new ObjX("remit","TH","THB"); obj3 =new ObjX("fund","SG","INR"); console.log(obj.trans()); console.log(obj.getData()); console.log(obj2.getData()); console.log(obj3.getData());

Try this magic!