Create data reports using JavaScript function

Assume you have a sporting event or league. The results are likely stored in a database and need to be displayed on a website. You can use the Fetch API to retrieve the data from the backend, although this document assumes the data has already been retrieved and is available as an array of records. This array must be in the correct order, but the source function can filter and sort the array on the fly within the report engine.

This document explains how to easily define headers and footers and arrange record grouping using compare function. Each header function returns HTML based on static text and parameters currentRecord, objWork, and splitPosition. Each footer function returns HTML based on static text and parameters previousRecord, objWork, and splitPosition. It is very flexible, but you have to create the HTML yourself; don't expect a WYSIWYG editor.

General structure of a report

A report consists of a report header and footer, which can be text, HTML, or both. The report contains one or more section levels:

• Section level N starts with header level N and ends with footer level N.
• Section level N contains one or more instances of section level N+1, except for the highest section level.
• The highest section level contains data created based on the records in the array, usually in the form of an HTML table or flex item.

Example of report structure

Structure of report definition object called reportDefinition

Examples of headers and footers array elements

Example of compare function

Running counter

In case you want to implement a running counter, you have to initialize/reset it in the right place. It can be achieved by putting some code in the relevant header:

If you only want to initialize objWork.runningCounter at the beginning of the report you can achieve that by putting the right code in reportDefinition.headers[0]. I call it property runningCounter, but you can give it any name you want.

You have to increase the running counter somewhere in your code because... otherwise it is not running ;-) for example:

Most of the time you don't need to manage a running counter in javascript! Most likely data comes from a database which can be queried by SQL. Use the SQL WINDOW function ROW_NUMBER or RANK to do the hard work.

How to create totals for multiple section levels, a running total and even a numbered header

How to preprocess the source array on the fly (for example in click event)

How to generate the report

Source code

Below source code I created to make this all work. It is kind of wrapper function for all headers and footers. Feel free to copy paste it and use it in your own module.

What is objWork

objWork is a javascript object that is passed as the second argument to createOutput function (optional argument, default {}). It is passed on as shallow copy to headers functions, footers functions, compare function, init function, source function and display function. All these functions share this object. You can use it for example for configuration information or color scheme. objWork is automagically extended with { rawData: thisData }. For example createOutput(reportDefinition, { font: 'Arial', font_color: 'blue' })(thisData).

Examples