Handling Nested Objects in a Multi-Page Form with Local Storage

Handling Nested Objects in a Multi-Page Form with Local Storage

When working with multi-page forms in TypeScript, it is common to encounter situations where you need to handle nested objects. This can be a bit tricky, especially when you want to persist the form data across different pages using local storage. In this blog post, we will explore different approaches to handle nested objects in a multi-page form and store the data in local storage.

Approach 1: Using JavaScript Object Notation (JSON)

One way to handle nested objects in a multi-page form is by using JavaScript Object Notation (JSON). JSON provides a convenient way to represent complex data structures, including nested objects. Here’s an example of how you can use JSON to handle nested objects:

const formData = {
  page1: {
    firstName: '',
    lastName: '',
  },
  page2: {
    address: '',
    city: '',
    state: '',
  },
};

// Set form data in local storage
localStorage.setItem('formData', JSON.stringify(formData));

// Get form data from local storage
const storedFormData = JSON.parse(localStorage.getItem('formData') || '');

// Update form data
storedFormData.page1.firstName = 'John';
storedFormData.page1.lastName = 'Doe';

// Store updated form data in local storage
localStorage.setItem('formData', JSON.stringify(storedFormData));

In this approach, we define a nested object called formData that represents the structure of our multi-page form. We then use JSON.stringify() to convert the object into a string and store it in local storage using localStorage.setItem(). To retrieve the form data, we use JSON.parse() to convert the string back into an object.

Approach 2: Using TypeScript Classes

Another approach to handle nested objects in a multi-page form is by using TypeScript classes. Classes provide a way to define complex data structures with built-in methods and properties. Here’s an example of how you can use classes to handle nested objects:

class Page1 {
  firstName: string = '';
  lastName: string = '';
}

class Page2 {
  address: string = '';
  city: string = '';
  state: string = '';
}

class FormData {
  page1: Page1 = new Page1();
  page2: Page2 = new Page2();
}

// Set form data in local storage
const formData = new FormData();
localStorage.setItem('formData', JSON.stringify(formData));

// Get form data from local storage
const storedFormData = JSON.parse(localStorage.getItem('formData') || '');
const parsedFormData = Object.assign(new FormData(), storedFormData);

// Update form data
parsedFormData.page1.firstName = 'John';
parsedFormData.page1.lastName = 'Doe';

// Store updated form data in local storage
localStorage.setItem('formData', JSON.stringify(parsedFormData));

In this approach, we define TypeScript classes for each page of our multi-page form. We then create a top-level class called FormData that contains instances of the page classes. We use JSON.stringify() and JSON.parse() to store and retrieve the form data in local storage, similar to the previous approach. The advantage of using classes is that it provides a more structured and organized way to handle nested objects.

Conclusion

Handling nested objects in a multi-page form with local storage can be challenging, but with the right approach, it becomes manageable. In this blog post, we explored two different approaches: using JSON and using TypeScript classes. Both approaches have their own advantages, so choose the one that best fits your project’s requirements. Remember to use JSON.stringify() and JSON.parse() to store and retrieve the form data in local storage.

By effectively handling nested objects in a multi-page form, you can ensure a smooth user experience and seamless data persistence. Happy coding!