Time · GitBook

# Time Cartesian Axis

The time scale is used to display times and dates. When building its ticks, it will automatically calculate the most comfortable unit base on the size of the scale.

## Configuration Options

The following options are provided by the time scale. They are all located in the `time` sub options. These options extend the common tick configuration.

Name | Type | Default | Description
--- | --- | --- | ---
`displayFormats` | `Object` |  | Sets how different time units are displayed. more...
`isoWeekday` | `Boolean` | `false` | If true and the unit is set to 'week', iso weekdays will be used.
`max` | Time |  | If defined, this will override the data maximum
`min` | Time |  | If defined, this will override the data minimum
`parser` | `String` or `Function` |  | Custom parser for dates. more...
`round` | `String` | `false` | If defined, dates will be rounded to the start of this unit. See Time Units below for the allowed units.
`tooltipFormat` | `String` |  | The moment js format string to use for the tooltip.
`unit` | `String` | `false` | If defined, will force the unit to be a certain type. See Time Units section below for details.
`unitStepSize` | `Number` | `1` | The number of units between grid lines.
`minUnit` | `String` | `millisecond` | The minimum display format to be used for a time unit.

## Date Formats

When providing data for the time scale, Chart.js supports all of the formats that Moment.js accepts. See Moment.js docs for details.

## Time Units

The following time measurements are supported. The names can be passed as strings to the `time.unit` config option to force a certain unit.

- millisecond
- second
- minute
- hour
- day
- week
- month
- quarter
- year

For example, to create a chart with a time scale that always displayed units per month, the following config could be used.

    var chart = new Chart(ctx, {
        type: 'line',
        data: data,
        options: {
            scales: {
                xAxes: [{
                    time: {
                        unit: 'month'
                    }
                }]
            }
        }
    })

## Display Formats

The following display formats are used to configure how different time units are formed into strings for the axis tick marks. See moment.js for the allowable format strings.

Name | Default
--- | ---
millisecond | 'SSS [ms]'
second | 'h:mm:ss a'
minute | 'h:mm:ss a'
hour | 'MMM D, hA'
day | 'll'
week | 'll'
month | 'MMM YYYY'
quarter | '[Q]Q - YYYY'
year | 'YYYY'

For example, to set the display format for the 'quarter' unit to show the month and year, the following config would be passed to the chart constructor.

    var chart = new Chart(ctx, {
        type: 'line',
        data: data,
        options: {
            scales: {
                xAxes: [{
                    type: 'time',
                    time: {
                        displayFormats: {
                            quarter: 'MMM YYYY'
                        }
                    }
                }]
            }
        }
    })

## Parser

If this property is defined as a string, it is interpreted as a custom format to be used by moment to parse the date.

If this is a function, it must return a moment.js object given the appropriate data value.

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