在对象的回调中将值从一种方法返回到第二种

Question

I have big object which basically is responsible for whole converting money.

Within this object I've got 4 methods.

addTaxAndShowBack() is my " main " method and it executes others as a chain with some kind of callback hell.

addTaxAndShowBack: function(priceField,selectedCurrency) {
    var that = this;
    var convertedToUSD = this.convertToUSD(priceField,selectedCurrency)
        .then(function(response) {
            console.log(response);
            var priceInUSD = response;
            that.addTax(priceInUSD,selectedCurrency)
                .then(function (response) {

                    console.log(response); // !!! THIS CONSOLE.LOG DOESN'T LOG ANYTHING

                }, function () {
                    console.log('error');
                });

        }, function (response) {
            console.log(response);
        });
},

First executed method ( convertedToUSD() ) is working fine it returns converted money from user default currency to USD. Second one is addTax() and it doesn't return value how I would like to. The console.log(response) doesn't log anything. The code of addTax method is:

addTax: function(priceInUSD, selectedCurrency) {
    var finalPriceInUSD;
    if(priceInUSD<300){
        // i should also store userPriceInUSD in some variable
        // maybe rootScope to send it to backend
        finalPriceInUSD = priceInUSD*1.05;
        console.log('after tax 5%: '+finalPriceInUSD);
        return finalPriceInUSD;
    } else {
        finalPriceInUSD = priceInUSD*1.03;
        console.log('after tax 3%: '+finalPriceInUSD);
        return finalPriceInUSD;
    }
},

I'm probably doing something wrong in addTax() not returning correctly or not assigning it correctly in addTaxAndShowBack() I don't know and that's why I need your help.

return finalPriceInUSD; this is what response in addTaxAndShowBack() in second callback should be.

Answer 1

You are not returning a promise. Try this

addTax: function(priceInUSD, selectedCurrency) {
    var finalPriceInUSD;
    if(priceInUSD<300){
        // i should also store userPriceInUSD in some variable
        // maybe rootScope to send it to backend
        finalPriceInUSD = priceInUSD*1.05;
        console.log('after tax 5%: '+finalPriceInUSD);
        return new Promise(res => { res(finalPriceInUSD) });
    } else {
        finalPriceInUSD = priceInUSD*1.03;
        console.log('after tax 3%: '+finalPriceInUSD);
        return new Promise(res => { res(finalPriceInUSD) });
    }
},