The `userCallback` method may be used for advanced tick customization. The following callback would display every label in scientific notation
```javascript
{
scales: {
xAxes: [{
ticks: {
// Return an empty string to draw the tick line but hide the tick label
// Return `null` or `undefined` to hide the tick line entirely
userCallback: function(value, index, values) {
return value.toExponential();
}
}
}]
}
}
```
#### Category Scale
The category scale will be familiar to those who have used v1.0. Labels are drawn in from the labels array included in the chart data.
The category scale extends the core scale class with the following tick template:
```javascript
{
position: "bottom",
}
```
#### Linear Scale
The linear scale can be used to display numerical data. It can be placed on either the x or y axis. The scatter chart type automatically configures a line chart to use one of these scales for the x axis.
The linear scale extends the core scale class with the following tick template:
```javascript
{
position: "left",
}
```
#### Logarithmic Scale
The logarithmic scale is used to display logarithmic data of course. It can be placed on either the x or y axis.
The log scale extends the core scale class with the following tick template:
The time scale is used to display times and dates. It can be placed on the x axis. When building its ticks, it will automatically calculate the most comfortable unit base on the size of the scale.
The time scale extends the core scale class with the following tick template:
```javascript
{
position: "bottom",
time: {
// string/callback - By default, date objects are expected. You may use a pattern string from http://momentjs.com/docs/#/parsing/string-format/ to parse a time string format, or use a callback function that is passed the label, and must return a moment() instance.
format: false,
// string - By default, unit will automatically be detected. Override with 'week', 'month', 'year', etc. (see supported time measurements)
unit: false,
// string - By default, no rounding is applied. To round, set to a supported time unit eg. 'week', 'month', 'year', etc.
round: false,
// string - By default, is set to the detected (or manually overridden) time unit's `display` property (see supported time measurements). To override, use a pattern string from http://momentjs.com/docs/#/displaying/format/