Nowadays, no ane wants to wait for anything. Everyone wants a quick issue. And immediate results either stem out of personal expertise or by hiring skilful Magento developers. Magento ii introduces the Knockout js, which is 1 of the critical factors in page loading speed.

What Is Knockout JS?

Knockout JS is a JavaScript library that helps to create responsive displays and an easy user interface. If you take sections of UI that update dynamically, KnockOut may help you implement those sections quickly.

As of now, Magento just implemented Knockout Js in the mini cart and checkout section, only we can also enhance the component and use JS layout in our custom sections.

Here we will talk over the different strategies of debugging the knockout JS errors

1) Binding Errors

This is the well-nigh mutual error we confront while binding data using js components in the layout file. Y'all meet this error might be due to incorrect information binding or incorrect syntax. At that place are several ways to overcome this error. Merely the challenging chore is to place which data are existence used for binding or which component is used for the bounden.

One of the fastest ways is to use the "pre" tag. Knockout js has its function called "ko.toJSON". This function volition offset create the Javascript object, and and then it will convert all the KO variables into the normal variables. You lot can apply pre tag similar this.

<pre data-bind="text: ko.toJSON($bindingData, null, 2)" />

"Ko.json" is the aforementioned as "JSON.stringify," and so you tin also apply the "JSON.stringify" as well. This method is too useful to know the information of context variables. For example, rather than "$bindingdata," you tin can employ $parent, $root, etc. likewise.

This function will give y'all output in JSON format like below

{

"data":

[

   {

     "id": 1,

     "name": "Knockout Detail 1"

},

   {

     "id": 2,

     "name": "Knockout Item two"

   }

]

}

This is non over here. There is an alternate option for the pre tag also. Y'all can also utilize the "console.log()" in your data binding. Hither is the syntax for the same

<div information-demark="apathetic: console.log($bindingdata)">

ii) Failed To Load Component

While implementing the Knockout js department, yous might accept seen the error in loading components. The js file shows condition code 404. There are multiple means you tin can include the JS component. Then it depends on how you have implemented the JS.

Include js Using XML Layout

Yous need to mention the vendor name and module name while adding js. Here is the syntax for XML layout

<item name="component" xsi:type="cord">VENDOR_MODULE/js/view/JSNAME</particular>

Ensure yous accept placed your js file in the right path and the vendor and module name are valid in the XML layout.

Include from Phtml

<script type="text/x-magento-init">

      {

          "[Telescopic]": {

              "VENDOR_MODULE/js/view/JSNAME": {}

          }

      }

  </script>

If y'all are loading components using phtml, the pattern for the file path volition remain the same. You lot merely demand to make sure of the scope of the chemical element. This is an alternate solution, but I volition recommend using the layout structure.

iii) Debug With Chrome DevTools

All the latest browsers support a debugging tool to find and prepare errors more easily. Let'south consider you are using the chrome browser. Follow the beneath steps to use debugging tools.

  • Open up your web page in chrome browser
  • Right-click and click on inspect element or press F12
  • Click on the sources tab
  • Open your loaded file using Ctrl + P

Hither you can open all the Javascript files and HTML files. Y'all can likewise add a breakpoint in the file. A breakpoint is the line of lawmaking that allows you to pause the script execution and debug the code. Once y'all set the breakpoint to refresh the page. Your script execution will suspension when you lot accomplish the breaking bespeak.

four) Undefined Variable

This is another most mutual result after binding. When you bind the holding of a variable that is not defined in the component, and so it will show the error of an undefined variable. You can trace this error from the browser console and also check the related component path as well.

It might be possible that you accept already defined the variable in the component, and still, yous can not access that variable in the template file. There is a case when you are playing inside the loop or whatsoever office. To employ the variable, you need to apply $parent property.

<span data-bind="text: $parent.yourvariable">

Final Notes

Knockout js the javascript library, so you need to be careful when finding any exceptions in components while debugging and fixing those errors. If knockout js finds any exception at the starting, it volition not render the consummate section. The best do is to use the try and catch within your component. In case you want help to troubleshoot knockout JS in Magento 2, you lot can connect with our team to hire Magento developers. Likewise, knockout js will ever throw an exception from the cadre library. I strongly do non recommend debugging the core library.

In instance you need help troubleshooting or something else Magento-related, then get in touch on with u.s.!