将 watchPosition 与箭头功能一起使用

Question

我正在使用以下代码通过 watchPosition 获取用户位置。我还想为失败参数定义代码并将选项传递给 watchPosition，但我不确定代码应该放在哪里。

if (navigator.geolocation) {
      //Success callback defined, but where shouls fail & options go?
      var positionTimer = navigator.geolocation.watchPosition((position) => {
      var crd = position.coords;

      console.log("Updated user loc...");
      console.log(crd.latitude + " : " + crd.longitude);


      this.myLatitude = crd.latitude;
      this.myLongitude = crd.longitude;

      this.updateUserLocation();
    },
    console.warn("Error getting user location"),
    this.options);
}
else {
  alert("Geolocation not supported in your browser!");
}

Answer 1

给你：

const options = {};
const id = navigator.geolocation.watchPosition((pos) => {
    console.log(pos);
}, (err) => {
    console.log(err);
}, options)

Answer 2

这是你想要的：

const positionTimer = navigator.geolocation.watchPosition(
  (position) => {
    // Your success code here
    console.log(position);
  },
  (err) => {
    // Your error code here
    console.log(err);
  },
  {
    // Options here
  }
)

记住：

An arrow function expression has a shorter syntax than a function expression and does not bind its own this, arguments, super, or new.target. These function expressions are best suited for non-method functions, and they cannot be used as constructors.

来源：Arrow functions

你可以像使用普通的一样使用它们function改变的东西就是上面提到的。

你也可以声明你的箭头函数：

const success = (position) => { /* Success code here */ }
const error = (err) => { /* Error code here */ }
const options = { /* Options... */ }

const positionTimer = navigator.geolocation.watchPosition(success, error, options);

将 watchPosition 与箭头功能一起使用

Using watchPosition with arrow function

javascript

arrow-functions