Invalid day index error caused by Nan value in columnIndexByDate

Gantt
#1

disclaimer: I’m not a javascript developer so my ways of determining the root cause may not be ideal.

I added baselines in my setup.

I get loads of “invalid day index” errors. Sometimes when changing scales (Im using zoom extension), sometimes after dragging a task. The error while dragging does not happens all the time, I haven’t figured the exact pattern yet.

I debugged into the code, it is always caused by a NaN value in columnIndexByDate because this statement results in NaN

 var part = (date22 - days[visibleIndex]) / this._getColumnDuration(this._tasks, days[visibleIndex]);

more specifically,

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Im gonna assume this is because the date22 is a string and days[visibleIndex] is a Date object

some calculation are done with that part variable and returned, also in the form of NaN

the next line does an assert, which leads to the error

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Digging deeper, I find that those String objects are coming from the baselines. bort start_date and end_date are strings.

The problem is that I integrated everything in a java environment, its not easy to get a 1-on-1 reproducible sample in pure js. I will try to create one.

#2

Hello,

It looks like you’re using a custom implementation of baselines, rather than the built-in baseline support provided by Gantt:
https://docs.dhtmlx.com/gantt/desktop__inbuilt_baselines.html#baselines

When using a custom solution, Gantt doesn’t automatically parse date strings into Date objects. This can lead to issues when Gantt performs internal date calculations.

If that’s the case, you’ll need to manually convert those string dates into actual Date objects before using them in Gantt:

gantt.attachEvent('onTaskLoading', function(task) {
	task.planned_start = gantt.date.parseDate(task.planned_start, gantt.config.date_format);
	task.planned_end = gantt.date.parseDate(task.planned_end, gantt.config.date_format);
	return true;
});

Please see an example: DHTMLX Snippet Tool