how to format time on xAxis use d3.js

I want to add this link to an awesome demo page. It is a playground when you can choose what a format specifier do you need for your case. It is very useful when you do not remember/know what a format specifier you should pass to your d3.timeFormat function.

I also want to notice, that if you have d3 version 4, you should use d3.timeFormat function, instead of d3.time.format.

You can use the tickFormat function on the axis object as below

var xAxis = d3.svg.axis()
    .scale(x)
    .orient("bottom")
    .tickFormat(d3.time.format("%H"));

The %H specifies hour (24-hour clock) as a decimal number [00,23]. Check this link D3 time formatting for more information

You can check out a working example in this tributary 24hr time example

The accepted answer is indeed correct, but in my case, I needed the flexibility for the formats to adjust to different scales (think zooming), but also to ensure the 24hr clock is used. The key is to define a multi-resolution time format. See the Documentation page for details.

My code:

var axisTimeFormat = d3.time.format.multi([
    [".%L", function(d) { return d.getMilliseconds(); }],
    [":%S", function(d) { return d.getSeconds(); }],
    ["%H:%M", function(d) { return d.getMinutes(); }],
    ["%H:%M", function(d) { return d.getHours(); }],
    ["%a %d", function(d) { return d.getDay() && d.getDate() != 1; }],
    ["%b %d", function(d) { return d.getDate() != 1; }],
    ["%B", function(d) { return d.getMonth(); }],
    ["%Y", function() { return true; }]
 ]);

var xAxis = d3.svg.axis()
    .scale(x)
    .orient("bottom")
    .tickFormat(axisTimeFormat);