What is the correct way to utilize Global Variables in programming?

Having trouble incrementing the current page in my pagination script to call the next page via AJAX...

In my TypeScript file, I declare a global variable like this;

declare var getCurrentPage: number;

Later in the same file, I set the value for getCurrentPage from my initial AJAX call

globalThis.getCurrentPage = data && data.startPage;
currentPage: getCurrentPage || 0,

This setup allows for flexibility as currentPage could have different values or default to zero if getCurrentPage is not available.

In my pagination file separate from the above (to account for initial AJAX-derived values), I attempt to increment my values and update the global variable accordingly

const nextPage = this.currentPage + 1;
globalThis.getCurrentPage = nextPage;

However, this leads to nextPage being 1 and currentPage remaining at 0. When pressing the Next Page button, the values stay the same because 0 + 1 equals 1...

What could be causing this issue?

Answer №1

It appears there may be a misunderstanding in how you are managing the global variable getCurrentPage. From your explanation, it seems like the variable currentPage is initially set to the value of getCurrentPage. However, when you increment currentPage, you are updating the value of getCurrentPage, which is not the intended behavior.

Here are the correct steps to follow:

  1. First, ensure that the global variable getCurrentPage is defined and accessible from both the initial TypeScript file and the pagination file.

  2. In the initial TypeScript file, after receiving data from an AJAX call, set the value of currentPage based on the response:


    declare var getCurrentPage: number;
    
    // After AJAX call
    globalThis.getCurrentPage = data && data.startPage;
    const currentPage = getCurrentPage || 0;

  1. In the pagination file, increment the value of currentPage and then update the global variable getCurrentPage with this new value:

    // In pagination file
    const nextPage = currentPage + 1;
    globalThis.getCurrentPage = nextPage;

Following these steps will correctly increment the value of currentPage and update the global variable getCurrentPage with the latest value. Clicking the Next Page button should now behave as expected.

Be sure to thoroughly review your code for any other areas that could be impacting functionality and avoid inadvertently reinitializing the currentPage variable elsewhere. Additionally, exercise caution when using global variables as they can introduce unpredictable behavior and complicate code maintenance. Consider employing proper encapsulation and scoping practices to manage state more effectively.

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