Display completed tasks in a line chart - No Daily Notes

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Hello, thank you for your reply. I will try and clarify things.

As I mentioned, dataview adds the completion date to completed tasks. As I read in this thread this information can be called by

TASK 
WHERE completion != null AND completion = date("YOUR DATE IN FORMAT YYYY-MM-DD")

also it does suggest the following query for pages with completed tasks of the last 7 days:

TABLE WITHOUT ID (filter(file.tasks, (t) => t.completion >= date(now) - dur(7 d)).text) AS " task completed this week"
WHERE file.tasks.completed AND file.tasks.annotated

However I think the main issue are the days where 0 tasks were completed. Since I would like the information to be displayed in a chart, if these days are not accounted for, the line graph would be misleading. The only way I can figure how these days could be included is by having a loop compare the list of tasks with the list of dates and count the instances.

So a script would need to generate a list of the last 7 days, I assume something like

function getLastSevenDays() {
    const dates = [];
    for (let i = 6; i >= 0; i--) {
        const date = new Date();
        date.setDate(date.getDate() - i);
        dates.push(date.toISOString().split('T')[0]); // Get date in yyyy-mm-dd format
    }
    return dates;
}

And then compare that list with the list of the tasks and count the instances:

// Function to compare List A with List B and create List C
function compareDates(listA, listB) {
    const listC = [];
    for (const dateA of listA) {
        let count = 0;
        for (const dateB of listB) {
            if (dateA === dateB) {
                count++;
            }
        }
        listC.push(count);
    }
    return listC;
}

I just have trouble putting it all together. I will look into your suggestion and see how far I can get. My bigges hinderance is that I dont really know how to debug these javascript functions step by step. Guess I have some reading to do.