javascript - 如何在 React 中将地理位置经纬度从一个函数传递到另一个函数的 `ll` 属性？

Question

我有一个 Geolocation.js，它获取地理位置并将其记录到控制台。这是导入到 index.js 文件中，需要使用那些 lat和 lng记录的值，以替换 ll 中的当前硬编码值其中:

import * as fsAPI from "../data/API_credentials";
import {userGeo} from "../component/Geolocation"

class Helper {
        static baseURL() {
            return "https://api.foursquare.com/v2";
        }
        // Client ID, client secret, and version stored in credentials file
        static auth(){
            const keys = {
                client_id: `${fsAPI.client_id}`,
                client_secret: `${fsAPI.client_secret}`,
                v: `${fsAPI.client_version}`,
                // Trying to get data from {userGeo} 
                // ll: `${userGeo.pos.lat}` + "," + `${userGeo.pos.lng}` //cannot read 'pos' of undefined.
                // Line below works
                ll: "36.04,-86.74"
            }
            return Object.keys(keys).map(key => `${key}=${keys[key]}`)
            .join("&");


        }

我导入的代码为 userGeo进入上面的代码如下，那是我的错误。我如何重构它以允许我获取 lat lng在ll多于？ userGeo.pos.lat例如。

你可以在 // ll: `${userGeo.pos.lat}` + "," + `${userGeo.pos.lng}` 中看到我失败的尝试, 抛出 cannot read 'pos' of undefined.

// Geolocation of user to be used for search query Foursqaure call url

export const userGeo = navigator.geolocation.getCurrentPosition((position) => {
    var pos = {
        lat: position.coords.latitude,
        lng: position.coords.longitude
    };

    console.log(pos) // works
    console.log("Lat: " + pos.lat) // works
});

非常感谢! 本

Answer 1

navigator.geolocation.getCurrentPosition 是异步的。它接受回调作为第一个参数，将在检索位置后调用。我的建议是在 auth 函数中 promise 并使用它:

// Geolocation.js

export const getUserGeo = function (options) {
  return new Promise(function (resolve, reject) {
    navigator.geolocation.getCurrentPosition(resolve, reject, options);
  });
}

// Helper.js

import { getUserGeo } from "../component/Geolocation";

class Helper {
        static baseURL() {
            return "https://api.foursquare.com/v2";
        }

        static auth(){
            return getUserGeo()
               .then(position => {
                   const keys = {
                      client_id: `${fsAPI.client_id}`,
                      client_secret: `${fsAPI.client_secret}`,
                      v: `${fsAPI.client_version}`,
                      ll: `${position.coords.latitude}` + "," + `${position.coords. longitude}` 
                  };
                  return Object.keys(keys).map(key => `${key}=${keys[key]}`).join("&"); 
               });
}

请记住，不是 auth() 方法是异步的，它返回一个 Promise，它将使用 Object.keys(keys ).map(key =>${key}=${keys[key]}).join("&")