Troubleshooting anonymous function scoping problems in JavaScript

Question

Troubleshooting anonymous function scoping problems in JavaScript

Currently, I am delving into WebGL concepts by utilizing JavaScript and the Three.js library. However, I have encountered a hurdle while attempting to load a .obj file using classes with the OBJLoader. Below is the code snippet that I am struggling with:

Model.prototype.loadModel = function () {
    var self = this;
    loader = new THREE.OBJLoader();

    loader.load( this.modelPath, function ( object ) {
        object.traverse( function ( child ) {
            if ( child instanceof THREE.Mesh ) {
                child.material.map = self.modelTexture;
            }
        });
        self.modelObj = object;
        console.log(self.modelObj); // Returns [Object object]
    });
        console.log(self.modelObj); // Returns undefined

    this.modelObj = self.modelObj;
    this.modelObj.position.x = this.x;
    this.modelObj.position.y = this.y;
    this.modelObj.position.z = this.z;
}

I seem to be unable to access the object as this.modelObj outside of the anonymous function, leading me to believe it's a scope-related issue. When trying to include this.modelObj in the function parameters, I get an error stating "missing formal parameter", and attempting to use this. inside the function implies it is within the function's scope or the loader itself.

javascript three.js anonymous-function scoping

Answer 1

Answer №1

If you want a callback to trigger upon completion of the loading process, simply include the callback as an argument in your function:

Model.prototype.loadModel = function (callback) {
    var self = this;
    var loader = new THREE.OBJLoader();

    loader.load(this.modelPath, function (object) { // function inside will execute on success
        object.traverse(function (child) {
            if (child instanceof THREE.Mesh)
            {
                child.material.map = self.modelTexture;
            }
        });

        self.modelObj = object;
        callback(object); // pass loaded object to the callback function
    });
}

By structuring it this way, you separate the loading mechanism from the callback, where the data can be utilized. It streamlines the process for handling multiple similar cases without repeating the loading logic each time.

The XHR (used in AJAX) also supports an error function and necessitates checking for a readystate variable within functions. It's unclear if the same applies to this specific loader, but incorporating error handling would be beneficial if feasible.

Answer 2

If you want a callback to trigger upon completion of the loading process, simply include the callback as an argument in your function:

Model.prototype.loadModel = function (callback) {
    var self = this;
    var loader = new THREE.OBJLoader();

    loader.load(this.modelPath, function (object) { // function inside will execute on success
        object.traverse(function (child) {
            if (child instanceof THREE.Mesh)
            {
                child.material.map = self.modelTexture;
            }
        });

        self.modelObj = object;
        callback(object); // pass loaded object to the callback function
    });
}

By structuring it this way, you separate the loading mechanism from the callback, where the data can be utilized. It streamlines the process for handling multiple similar cases without repeating the loading logic each time.

The XHR (used in AJAX) also supports an error function and necessitates checking for a readystate variable within functions. It's unclear if the same applies to this specific loader, but incorporating error handling would be beneficial if feasible.

Answer 3

Answer №2

The issue here is not related to scoping. The main problem lies in the fact that loader.load operates as an asynchronous function call, similar to AJAX. Therefore, utilizing a callback is essential in order for your code to function correctly.

Answer 4

The issue here is not related to scoping. The main problem lies in the fact that loader.load operates as an asynchronous function call, similar to AJAX. Therefore, utilizing a callback is essential in order for your code to function correctly.

Troubleshooting anonymous function scoping problems in JavaScript

Answer №1

Answer №2

Similar questions

retrieving the webpage's HTML content from the specified URL using AngularJS

Understanding the default value type in React's setState method

Ways to thwart CSRF attacks?

Is there a way to verify if a value is undefined before including it as an object field?

Assign a specific value to ngModel in Angular 4

JavaScript Popup Box Failing to Trigger

What is the most effective method for displaying an error code when a JavaScript error occurs?

Using v-model to dynamically update the router based on certain conditions

Issues with MySQL not functioning properly when using Promise.All in a Node.js environment

Optimizing Angular.js templates for faster loading using Node.js pre-compilation

Navigate through collections of objects containing sub-collections of more objects

React sends a POST request that returns with an empty body

Efforts to toggle visibility of icons in React

The icon on my page is not displaying, and the responsive menu is also not appearing

Steps to ensure that Vue data is updated to accurately reflect any modifications made by user input in the HTML

Looking for assistance with troubleshooting my isotope.js [code written in jquery and html]?

Express identifies the user, however, the username is displayed exclusively on one specific page. This situation may indicate a potential cookie problem

Scroll through the menu with ease

Leverage the power of Angular's $http module in conjunction with Django's urlpatterns to fetch

What are the recommended techniques for utilizing prototypal and prototype-based inheritance in modern JavaScript (ES6) and TypeScript?