axis.tickValues()

axis.tickValues([values])

If a values array is specified, the specified values are used for ticks rather than using the scale’s automatic tick generator. If values is null, clears any previously-set explicit tick values and reverts back to the scale’s tick generator. If values is not specified, returns the current tick values, which defaults to null. For example, to generate ticks at specific values:

var xAxis = d3.axisBottom(x)
    .tickValues([1, 2, 3, 5, 8, 13, 21]);

The explicit tick values take precedent over the tick arguments set by axis.tickArguments. However, any tick arguments will still be passed to the scale’s tickFormat function if a tick format is not also set.