length

Takes a GeoJSON and measures its length in the specified units, (Multi)Point 's distance are ignored.
采用GeoJSON并以指定的单位度量其长度，忽略(Multi)点的距离。

参数

参数	类型	描述
geojson	GeoJSON	GeoJSON to measure
options	Object	Optional parameters: see below

options选项

属性	类型	默认值	描述
units	string	kilometers	can be degrees, radians, miles, or kilometers

返回

number - length of GeoJSON

示例

var line = turf.lineString([[115, -32], [131, -22], [143, -25], [150, -34]]);
var length = turf.length(line, {units: 'miles'});