Comfino installments

Embedding the widget on the page

To embed the widget on a product page, the following initialization code should be included:

var script = document.createElement('script');
script.onload = function () {
        widgetKey: 'WIDGET_KEY',
        priceSelector: 'WIDGET_PRICE_SELECTOR',
        widgetTargetSelector: 'WIDGET_TARGET_SELECTOR',
        priceObserverSelector: 'WIDGET_PRICE_OBSERVER_SELECTOR',
        priceObserverLevel: WIDGET_PRICE_OBSERVER_LEVEL,
        type: 'WIDGET_TYPE',
        offerType: 'OFFER_TYPE',
        embedMethod: 'EMBED_METHOD'
script.src = '//';
script.async = true;
  • Basic widget configuration options:

    • widgetKey - widget API key which enables calculations and downloading the offer from the Comfino API
    • priceSelector - selector of the element which contains the price of the product (eg: span[itemprop=price], details in section "Additional information")
    • widgetTargetSelector - selector of the element which is the container of the widget (eg: div.product-actions, details in section "Additional information")
    • priceObserverSelector - selector of the observed parent element that contains the price element (details in section "Additional information")
    • priceObserverLevel - DOM hierarchy level used for tracking price changes and offer recalculation (level of the observed parent container relative to the price container, details in section "Additional information")
    • type - widget type (simple - textual, mixed - graphical with banner, with-modal - graphical with installments calculator, extended-modal - graphical with extended installments calculator)
    • offerType - offer type (INSTALLMENTS_ZERO_PERCENT - 0% installments, CONVENIENT_INSTALLMENTS - convenient installments, PAY_LATER - Pay later, COMPANY_BNPL - Deferred payment for companies)
    • embedMethod - widget embedding method (INSERT_INTO_FIRST, INSERT_INTO_LAST - default value, INSERT_BEFORE, INSERT_AFTER)
  • Additional widget configuration options

    • price - product price used for installments calculation (in case if set, priceSelector, priceObserverSelector and priceObserverLevel options are ignored)
    • numOfInstallments - number of installments for which the calculation is to be carried out and the offer returned (default: 0 - default number of installments for a given type of offer)
    • callbackBefore - callback function executed before downloading data from the API and displaying the widget (details in section "Callback functions")
    • callbackAfter - callback function executed after downloading data from the API and displaying the widget (details in section "Callback functions")
    • onOfferRendered - callback function executed after displaying the offer (details in section "Callback functions")
    • onGetPriceElement - callback function executed before getting the price (details in section "Callback functions")
  • where:

    • option - mandatory parameter
    • option - optional parameter

Widget script hosts

Widget types

  • Textual (simple)


  • Graphical with banner (mixed)


  • Graphical with installments calculator (with-modal)



  • Graphical with extended installments calculator (extended-modal)




Callback functions

  • callbackBefore

Callback function executed before downloading data from the API and displaying the widget.

Default implementation: function () {}

  • callbackAfter

Callback function executed after downloading data from the API and displaying the widget.

Default implementation: function () {}

  • onOfferRendered

Callback function executed after displaying the offer. Allows to make visual modifications to the displayed widget.

Default implementation: function (jsonResponse, widgetTarget, widgetNode) { }

Function arguments

{Object} jsonResponse: JSON object with the API response containing the calculated offer
{HTMLElement} widgetTarget: the page element where the widget was placed
{Document} widgetNode: DOM node containing the HTML structure of the widget

  • onGetPriceElement

Callback function executed before getting the price. It allows to influence the way the price is collected by substituting your own logic.

Default implementation: function (priceSelector, priceObserverSelector) { return null; }

Function arguments

{string} priceSelector: the current selector of the element which contains the price of the product
{string} priceObserverSelector: the current selector of the observed parent element which contains the price element

Additional information

Getting the loan amount for calculation and updating the calculation

An example of a price item on a product page.


Selector of the element with price (priceSelector parameter): span.current-price-value



The amount taken from the element indicated by priceSelector is used in the offer calculation as the credit amount.

In the case of products with several price variants, selecting a product option results in a dynamic price change and recalculation of the amount in the element indicated by priceSelector. However, the price change will not be detected by the widget and the calculated credit offer will remain unchanged. In order to activate the mechanism of automatic offer recalculation depending on dynamic changes in the product price, one of the following parameters should be used: priceObserverSelector, priceObserverLevel

If the entire content of the parent element containing the price element is changed, then the observation of the price element itself will not work properly, because it will be deleted along with all attached event observers, after each price change. In this situation, you must attach the observer to the element higher in the DOM hierarchy which contains the changed element and is not affected by the price change, which ensures that attached event observers are not lost. An attached change observer reacts to changes in the content of the indicated element down the hierarchy of the DOM tree. The image below shows the price element indicated by the span.current-price-value selector.

The priceObserverLevel parameter indicates how many levels above the span.current-price-value price element, the observer of changes in the content of the HTML element should be attached. In the case of the value 0, it is of course the same price element, for the value 1 - the level above div.current-price, for the value 3 - div.product-prices.js-product-prices, etc.


Alternatively, you can use the priceObserverSelector parameter to directly indicate which element to observe. This is a more convenient method than the relative element selection with priceObserverLevel shown earlier. However, if it is not possible to unambiguously indicate the observed element using the selector, it enables relative indication of the observed element in relation to the price element, without using the selector.

More about CSS selectors: MDN Web Docs - CSS selectors, MDN Web Docs - CSS selectors reference, MDN Web Docs - Document.querySelector()

Positioning the widget on the website

An example of widget location on the product page.


Container element selector (widgetTargetSelector parameter) where the widget is embedded: div.product-actions



Embedded widget.

Konfiguracja Konfiguracja

Widget embedding method

Container element - element of the HTML document indicated by the selector from the widgetTargetSelector parameter.

Available options:

  • INSERT_INTO_FIRST - inserting the widget element into the container element at the very beginning before the existing content
  • INSERT_INTO_LAST - inserting the widget element into the container element at the very end after the existing content
  • INSERT_BEFORE - inserting the widget element before the container element (visually above the container)
  • INSERT_AFTER - inserting the widget element after the container element (visually under the container)