Optimize category parse for usual use case

[kurkle]

When labels array contains item for each data point, the label is going to be at the same index.
So check there first, before going for indexOf.

With this chart:

function generateFakeData() {
	var res = [];
	var i = 0;
	for (i = 0; i < 50000; ++i) {
		res.push(i);
	}

	return res;
}

var chart = new Chart(ctx, {
	type: 'line',
	data: {
		labels: generateFakeData(),
		datasets: [
			{
				label: '# of Votes',
				data: generateFakeData()
			}
		]
	},
	options: {
		animation: false,
		tooltips: {
			intersect: false
		},
		scales: {
			y: {
				beginAtZero: true
			}
		}
	}
});

master:

pr:

[benmccann]

I'm not sure I understand why the label array would contain the data for that data point. Can you explain the use case a bit more with an example?

[kurkle]

https://www.chartjs.org/samples/master/charts/bar/stacked.html for example. Labels and data points are matched by index.
But if you have data: [{x: 'b', y: 1}, {x: 'a', y: 2}], labels: ['a', 'b'] the index won't match.