当位置服务关闭时，navigator.gelocation 在 iOS 上仍然为真

Question

Everything I've read says that in order to check if geolocation is available, to check for navigator.geolocation . However, on iOS with location services turned off it still passes the check.

It never reaches the else .

Note: I am testing over https.

if(navigator.geolocation)
{
    // on iOS safari, with location services off (globally or at the app level) this will log
    console.log('navigator.geolocation passes');
    // navigator.geolocation.getCurrentPosition does exist
    console.log(navigator.geolocation.getCurrentPosition);

    // attempt to make the call
    navigator.geolocation.getCurrentPosition((position)=>
    {
        // this will not get called
        console.log('successfully retrieved position')
    },
    (error)=>
    {
        // this will not get called
        console.log('error: ', error)
    })
}
else
{
    // I would expect this to be called but it doesn't get called
    console.log('geolocation unavailable')
}

Now, I'm not trying to get the location when location services are off, but the issue is that when they are off, it shouldn't pass the check.

I suppose as a last resort, I could just set a variable to the coordinates and check if they're undefined or rather than rely on the block above, but if there's a better way to check for it then I'd like to do that.

Edit: I should also mention that this only occurs on the first load of the page after browser settings have been cleared (at least in my case). On first load, it would pass the check and then hang because nothing else would be called. On second load it seemed to not pass the check and called our fallback option.

Edit: The solution is to set a variable outside of the check.

// create a variable to hold the coordinates
let _coords = undefined;
// this is only a compatibility check
// not a check if it's available
if(navigator.geolocation)
{
  // on iOS safari, with location services off (globally or at the app level)
  // this block will be reached

  // attempt to make the call to getCurrentPosition
  navigator.geolocation.getCurrentPosition((position)=>
  {
    // this will not get called because location services are off
    // doing something like doSomething(position.coords) will not get called
    // instead, set the variable
    _coords = position.coords;
  },
  (error)=>
  {
    // this will not get called since it's not an error
    // doSomething(undefined);
  })
}
else
{
    // this block will not get reached since geolocation IS available,
    // just not allowed. So again,
    // doSomething(undefined) will not happen
    console.log('geolocation unavailble')
}
// pass the variable (coords or undefined) to doSomething
doSomething(coords)

The above doesn't solve the entire issue since if the user does have locations services on, the getCoordinates is async so it will call the doSomething method before it receives the coordinates.

Answer 1

I think this checking is for compatibility by testing for the presence of the geolocation object:

// check for Geolocation support
if (navigator.geolocation) {
  console.log('Geolocation is supported!');
}
else {
  console.log('Geolocation is not supported for this Browser/OS.');
}

Answer 2

I spoke too soon, and accepted too soon. In my example, moving the method outside of the geolocation check resulted in always "failing" the geolocation check because getCurrentPosition is asynchronous. The fix (could have sworn I tried this before) is to use a try/catch in the check.

// geolocation
if(navigator.geolocation)
{
  // try to get the current position
  try {
    navigator.geolocation.getCurrentPosition((position)=>
    {
      // great success! use the coordinates
      doSomething(position.coords);
    },
    (err)=>
    {
      // failed
      console.log(err);
      // most likely due to a PositionError
      // err.code === 1 (PERMISSION_DENIED)
      doSomething();
    })

  } catch (err) {
    // any other error
    console.log(err);
  }
}
else
{
  // geolocation not supported
  doSomething();
}

function doSomething(coords=undefined)
{
  // ... 
}