Unable to execute a function within the same class in TypeScript

My experience with TypeScript is still fresh, and I've encountered an issue while trying to call a function within the same class. Here's the function in question:

createPost(url: String, data: any) {
    $.ajax({
      url: url + "/" + GLOBAL.REGISTER_URL,
      type: "POST",
      data: data.serialize(),
      success: function() {
        console.log("success");
      },
      error: function(request, status, error) {
        console.log(request.responseText);
        console.log(status);
        console.log(error);
      }
    });
  }

I'm attempting to invoke it here:

.on('success.form.bv', function(e) {
        $('#success_message').slideDown("slow"); // Do something ...
        $('#contact_form').data('bootstrapValidator').resetForm();

        // Prevent form submission
        e.preventDefault();

        // Get the form instance
        var $form = $(e.target);

        // Get the BootstrapValidator instance
        var bv = $form.data('bootstrapValidator');

        // Reassigning port for testing purposes only
        var result = "https://" + window.location.hostname + ":" + GLOBAL.PORT + "/" + GLOBAL.VERSION + "/rest" + GLOBAL.REGISTER_URL;

        this.createPost(result, $form);
      });

Unfortunately, this doesn't seem to be working as expected. Every time I click the button, I encounter an error in the browser:

ERROR TypeError: this.createPost is not a function Stack trace: ../../../../../src/app/register/register.component.ts/RegisterComponent.prototype.ngOnInit/<@http://localhost:4200/main.bundle.js:839:13 (error details)

Calling this function should be straightforward, but I'm puzzled by what could be causing this issue. Any assistance would be greatly appreciated.

Answer №1

It seems like the issue lies within the scope of your code. My suggestion would be to consider something along these lines:

.on('success.form.bv',(e) => { //<-- using an arrow function
        $('#success_message').slideDown("slow"); // Perform desired action ...
        $('#contact_form').data('bootstrapValidator').resetForm();

        // Prevent form submission
        e.preventDefault();

        // Obtain the form instance
        var $form = $(e.target);

        // Grab the BootstrapValidator instance
        var bv = $form.data('bootstrapValidator');

        // For testing purposes only, update port assignment
        var result = "https://" + window.location.hostname + ":" + GLOBAL.PORT + "/" + GLOBAL.VERSION + "/rest" + GLOBAL.REGISTER_URL;

        this.createPost(result, $form);
      });

Alternatively, you could encapsulate 'this' by:

var _that = this;
.on('success.form.bv', function(e) {
        $('#success_message').slideDown("slow"); // Perform desired action ...
        $('#contact_form').data('bootstrapValidator').resetForm();

        // Prevent form submission
        e.preventDefault();

        // Obtain the form instance
        var $form = $(e.target);

        // Grab the BootstrapValidator instance
        var bv = $form.data('bootstrapValidator');

        // For testing purposes only, update port assignment
        var result = "https://" + window.location.hostname + ":" + GLOBAL.PORT + "/" + GLOBAL.VERSION + "/rest" + GLOBAL.REGISTER_URL;

        _that.createPost(result, $form);
      });

Answer №2

Avoid using function {} in TypeScript; instead, opt for () => {} to ensure the preservation of the correct this reference.

If not, you will need to resort to (function() {}).bind(this) to maintain the desired scope for this.

.on('success.form.bv', (e) => {
    // ......
    this.createPost(result, $form);
  });

Answer №3

The issue you're facing is likely due to closures. While Typescript and Angular usually prevent this problem, it seems like jQuery may be causing some complications.

To resolve the issue:

Replace

createPost(url: String, data: any) {...}

with

createPost = (url: String, data: any) => {...}

Using the fat arrow or lambda function creates a lexical this which maintains its scope.

On a side note, I'm curious why jQuery is being used with Angular 2+. Angular already provides comprehensive functionality for DOM manipulation, so incorporating jQuery can unnecessarily complicate things and potentially undermine Angular's capabilities.

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