I have read a lot about promises but I'm still not sure how to implement it.

I wrote the folowing AJAX call with async=false in order for it to work, but I want to replace it with promise as I saw that async=false is deprecated.

self.getBalance = function (order) {
    var balance;
    $.ajax({
        url: "/API/balance/" + order,
        type: "GET",
        async: false,
        success: function (data) {
            balance = data;
        },
        done: function (date) {
        }
    });
    return balance;
}

Would you be able to help me? I just need an example to understand it.

I have read a lot about promises but I'm still not sure how to implement it.

I wrote the folowing AJAX call with async=false in order for it to work, but I want to replace it with promise as I saw that async=false is deprecated.

self.getBalance = function (order) {
    var balance;
    $.ajax({
        url: "/API/balance/" + order,
        type: "GET",
        async: false,
        success: function (data) {
            balance = data;
        },
        done: function (date) {
        }
    });
    return balance;
}

Would you be able to help me? I just need an example to understand it.

• javascript
• ajax
• asynchronous
• promise

• May be you should try to structure your logic to avoid async=false behaviors, If you are learning promises you should try to load things with promises each time you need them, but you can decide to catch them or not inside the promise method. – fbiagi Commented Aug 11, 2016 at 11:17

2 Answers 2

As first point, you don't want to set an asynchronous call to false as it will lock the UI.

You could simplify your method returning the ajax object and the handle it as a promise.

self.getBalance = function (orderNumber) {    
    return $.ajax({
        url: "/Exchange.API/accountInfo/balance/" + orderNumber,
        type: "GET",
    });
};
var demoNumber = 12;
self.getBalance(demoNumber).then(function(data){
    console.log(data);
},function(err){
    console.log("An error ocurred");
    console.log(err);
});

Return promise object from getBalance method:

self.getBalance = function (orderNumber) {
    return $.ajax({
        url: "/Exchange.API/accountInfo/balance/" + orderNumber,
        type: "GET"
    });
}

and use it later like this:

service.getBalance().then(function(balance) {
    // use balance here
});