computeddistance/lib/index.js

根据经纬度计算两地距离

/**
 * 计算两点之间的距离
 * 单位 km(千米)
 * @param {number} lng1 
 * @param {number} lat1 
 * @param {number} lng2 
 * @param {number} lat2 
 */
export const getDistance = (lng1, lat1, lng2, lat2) => {
    const EARTH_RADIUS = 6378.137
    const radLng1 = rad(lng1)
    const radLat1 = rad(lat1)
    const radLng2 = rad(lng2)
    const radLat2 = rad(lat2)

    const latDiff = radLat1 - radLat2
    const lngDiff = radLng1 - radLng2

    let distance = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(latDiff / 2), 2) + Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(lngDiff / 2), 2)));
    distance = distance * EARTH_RADIUS
    distance = Math.round(distance * 10000) / 10000
    
    return distance
}

/**
 * 计算多个经纬度的位置
 * 数组形式 [[lng, lat], [lng, lat]]
 * @param {[number, number][]} distances
 * @returns {number}
 */
export const computedMultiDistance = (distances) => {
    const maxLength = distances.length
    if (!Array.isArray(distances) || maxLength < 2) return 0.0

    let distance = 0.0
    for (let i = 0; i < maxLength - 1; i++) {
        const nowItem = distances[i]
        const nextItem = distances[i + 1]

        distances += getDistance(nowItem[0], nowItem[1], nextItem[0], nextItem[1])
    }

    return parseFloat(distance.toFixed(3))
}

/**
 * 经纬度转换
 * @param {number} du 
 */
export const rad = (du) => du * Math.PI / 180.0