How to Dynamically Calculate the Sum of Columns in Multiple Tables with JavaScript

Описание: Learn how to easily calculate the sum of a specific column across different tables using JavaScript. Enhance your web pages with this dynamic feature.
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This video is based on the question https://stackoverflow.com/q/64065342/ asked by the user 'SPL' ( https://stackoverflow.com/u/4512121/ ) and on the answer https://stackoverflow.com/a/64066517/ provided by the user 'PeterKA' ( https://stackoverflow.com/u/3558931/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Dynamically Calculate the Sum of Columns in Multiple Tables with JavaScript

Managing data tables on web pages can often be a challenging task, especially when you need to calculate and display totals dynamically. In this post, we'll explore how to sum up values from a specific column across multiple tables and present the results effectively on your web page using JavaScript.

The Problem

Imagine you have several tables populated with data fetched from a backend using PHP. Each table contains rows with a specific column indicating cubic measurements represented in m³. You want to calculate the total for this column and display it beneath each corresponding table.

For example, you might have tables structured like this:

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You can easily calculate the total for one specific table by using the class name corresponding to that table’s ID. However, the challenge arises when you want to do this dynamically for all tables without hardcoding values or duplicating code.

Step-by-Step Solution

1. Capture Tables with Target Columns

The first step is to capture all tables that contain your target columns (the ones with the m³ values). You can achieve this by using jQuery’s :has() selector.

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2. Process Each Table for Totals

Next, iterate through each of these captured tables. For each table, you will determine the corresponding total's ID and compute the sum of its values.

Determine the ID for Total Calculation

You need to get the ID where the total will be updated. Use the following line to extract the table ID dynamically:

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This code breaks down the process of extracting the table's numeric identifier from the class name (e.g., converting singleUnitCubic-13 into 13 for the total ID).

Calculate the Total

To compute the sum, use the map function along with reduce:

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3. Update the DOM with the Total

The final step is to inject this total back into the respective span element:

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Complete Code Example

Here’s the full JavaScript code that accomplishes all the above steps:

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Conclusion

With the code structure outlined above, you can efficiently sum up the values from specific columns across different tables within your web page. This approach not only eliminates redundancy but also enhances the user experience by providing real-time updates based on the displayed data.

Now you can enhance your web applications with this dynamic feature that streamlines data management effectively. Happy coding!