In d3.js ticks are not showing in the x axis - d3.js

Question

I am trying to show a barchart using d3.js. Y axis contains the speed and x axis contains time. I am using the following code:
var margin = {top: 20, right: 20, bottom: 70, left: 40},
width = 400 - margin.left - margin.right,
height = 250 - margin.top;
var x = d3.scale.ordinal().rangeRoundBands([ 0, width ], .1);
var y = d3.scale.linear().range([ height, 0 ]);
var xAxis = d3.svg.axis().scale(x).orient("bottom");
var yAxis = d3.svg.axis().scale(y).orient("left").ticks(20);
x.domain(data.map(function(d) { return d.datetime; }));
y.domain([0, d3.max(data, function(d) { return d.speed; })]);
var svg=d3.select("#bar").append("svg").attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom).append("g").attr("transform",
"translate(" + margin.left + "," + margin.top + ")");
var transition = svg.transition().duration(750), delay = function(d, i) {
return i * 50;
};
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis)
.selectAll("text")
.style("text-anchor", "end")
.attr("dx", "-.8em")
.attr("dy", "-.55em")
.attr("transform", "rotate(-90)" ).text("Time");
svg.append("g")
.attr("class", "y axis")
.call(yAxis)
.append("text")
.attr("transform", "rotate(-90)")
.attr("y", 6)
.attr("dy", ".71em")
.style("text-anchor", "end")
.text("Speed");
svg.selectAll("rect")
.data(data)
.enter().append("rect").transition().delay(0)
.style("fill", "red")
.attr("x", function(d,i) { return 30*i+20; })
.attr("width", 25)
.attr("y", function(d) { return y(d.speed); })
.attr("height", function(d) { return height - y(d.speed); }); //function(d){return " "+d.datetime;}
transition.select(".y.axis").call(yAxis);
But unfortunately no ticks are showing in the x axis. Y axis ticks are working fine. Can anyone help me regarding this?

Answer 1

In your x-axis creation, this:
.attr("transform", "rotate(-90)" ).text("Time");
is just going to but the word "Time" on each tick. What you need is:
// define the time format you want
var format = d3.time.format("%Y-%m-%d");
// create x axis
...
.text(function(d){
return format(d);
});
Also in your rect placement:
svg.selectAll("rect")
...
.attr("x", function(d,i) { return 30*i+20; })
You are spacing them based on index. You need to match this to the axis position:
svg.selectAll("rect")
...
.attr("x", function(d, i) {
return x(d.datetime);
})
Here's an example.

Answer 2

Your problem may be where you set the domain for x:
x.domain(data.map(function(d) { return d.datetime; }));
You probably want something like:
x.domain([d3.min(data, function(d) { return d.datetime; }), d3.max(data, function(d) { return d.datetime; })]);