Question

Basic D3.js question, getting to grips with the syntax!

I’m using D3 and I want to create an axis if it doesn’t exist, or update it with a transition if it does already exist.

My current code is below, but this code re-creates the axis each time – it doesn’t transition. How can I change it to transition?

var xAxis = d3.svg.axis().scale(x).orient("bottom").ticks(4).tickSize(6, 3, 0);

updateGraphAndAxes(initialdata);

$('#button').click(function() { 
  updateGraphAndAxes(newdata);
});

function updateGraphAndAxes(newdata) { 
  // update x.domain here using newdata, then... 
  svg.append("g")
   .attr("class", "x axis")
   .attr("transform", "translate(0," + height + ")")
   .call(xAxis);
} 

Answer 1

Following this example. The approach is like this:

var xAxisGroup = null;

function updateGraphAndAxes(newdata) { 

    var t = null;

    t = svg.transition().duration(1000);        // Set up transition

    // update x.domain using newdata... 

    if (!xAxisGroup) {
        xAxisGroup = svg.append("g")
            .attr("class", "xTick")
            .attr("transform", "translate(0," + height + ")")
            .call(xAxis);           
    } else {
        t.select('.xTick').call(xAxis);     // Call xAxis on transition
    }
}