时间比例尺

• d3.time.scale - construct a linear time scale.
• scale - get the range value corresponding to a given domain value.
• scale.invert - get the domain value corresponding to a given range value.
• scale.domain - get or set the scale's input domain.
• scale.nice - extend the scale domain to nice round numbers.
• scale.range - get or set the scale's output range.
• scale.rangeRound - set the scale's output range, and enable rounding.
• scale.interpolate - get or set the scale's output interpolator.
• scale.clamp - enable or disable clamping of the output range.
• scale.ticks - get representative values from the input domain.
• scale.tickFormat - get a formatter for displaying tick values.
• scale.copy - create a new scale from an existing scale.