What is the mean of This Code in js

Question

what does the below coding mean?

        !-- ko foreach: getRegion('messages') -->
          <!-- ko template: getTemplate() --><!-- /ko -->
        <!--/ko-->

Answer 1

It is a knockout.js code.

Magento 2 used knockout JS in several place like checkout, cart, UI component.

As per your query.

<!-- ko template: getTemplate() --><!-- /ko -->

Above code is call template file using knockout. and below code is for get validation error message.

<!-- ko foreach: getRegion('messages') -->

There are so many documentation available for knockout JS below is one of them.

• devdocs.magento.com
• knockout-js-in-magento-2

I hope it helps!

Answer 2

Adding to Chirag's answer
getRegion() is mapped against displayArea node
In your example displayArea is messages

Example: <item name="displayArea" xsi:type="string">messages</item>

getTemplate is mapped against template node and call the template, in your example it will call all the templates

Example: <item name="template" xsi:type="string">Magento_Checkout/onepage</item>

ko foreach: and ko template: are knockout js bindings

The foreach binding duplicates a section of markup for each entry in an array, and binds each copy of that markup to the corresponding array item.

The template binding populates the associated DOM element with the results of rendering a template.