在 navigator.geolocation.getCurrentPosition 之外保存变量?(javascript)

2022-01-14 00:00:00 geolocation javascript navigator w3c-geolocation

我正在尝试使用 js 的范围从 navigator.geolocation.getCurrentPosition 中拉出一个变量

I'm trying to play with the scope of js to pull a variable out of navigator.geolocation.getCurrentPosition

var lat;
function callback (position) {
    lat = position.coords.latitude;
}
navigator.geolocation.getCurrentPosition(callback,fail,{timeout:10000});
// after getCurrentPosition succeeds
alert(lat); // this alerts null

上面的代码因为作用域的原因，不能将 position.coords.latitude 存储在 lat 变量中.有没有办法做到这一点?

The above code cannot store position.coords.latitude in the lat variable because of the scope. Is there a way to do this?

推荐答案

你必须记住 asyncajax 的本质.

You have to remember the asyncajax nature.

这是你的代码的执行顺序:

this is the execution order of your code:

var lat;
alert(lat); // this alerts null
navigator.geolocation.getCurrentPosition(callback,fail,{timeout:10000});
function callback (position) {
    lat = position.coords.latitude;
}

这就是你得到 null 的原因.异步！，异步！ :)

This why you get null. async!, async! :)

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