Setting layout.xaxis.tickmode to 'array' explicitly does not work on date and log axes

[ark-ark]

Setting layout.xaxis.tickmode to array explicitly does not work at all. If set to array all settings regarding tickvals and ticktext will be ignored. tickvals and ticktext only have an effect if tickmode is not set.

See https://jsfiddle.net/xt6udrkh/2/

[etpinard]

Thanks for reporting.

The current logic is pretty clear:

plotly.js/src/plots/cartesian/tick_value_defaults.js

Lines 16 to 24 in c8a9f8a

	if(containerIn.tickmode === 'array' &&
	(axType === 'log' || axType === 'date')) {
	tickmode = containerOut.tickmode = 'auto';
	} else {
	var tickmodeDefault = Array.isArray(containerIn.tickvals) ? 'array' :
	containerIn.dtick ? 'linear' :
	'auto';
	tickmode = coerce('tickmode', tickmodeDefault);
	}

I'm not sure why tickmode is set to 'auto' here. Maybe tickvals / ticktext used to not work on date and log axes.

[etpinard]

Commit 355fb09 changed a few things and may be the culprit.

[etpinard]

and then there's this test:

plotly.js/test/jasmine/tests/axes_test.js

Lines 1538 to 1542 in c8a9f8a

	axIn = {tickmode: 'array', tickvals: [1, 2, 3]};
	axOut = {};
	mockSupplyDefaults(axIn, axOut, 'date');
	expect(axOut.tickmode).toBe('auto');
	expect(axIn.tickmode).toBe('array');

clearly 🔒 ing down the reported behavior 🤔

[archmoj]

Fixed via #4851.