So Safari keeps yelling at me for one specific error.
I'm trying to use Google Maps API and call map.getCenter();. However sometimes, this happens before the map has been fully loaded.
So instead in my function I test for an undefined call like this:
if (map.getCenter() != undefined)
But that still errors out because I guess it doesn't even like making the call just to test the if the result is undefined or not?
Can I get some help here?
Thanks!
I actually prefer something along these lines.
if(typeof myfunc == 'function') {
myfunc();
}
Just because something isn't undefined doesn't make it a function.
if(typeof myfunc !== 'function') { myfunc(); }
if(typeof myfunc !== 'function') { myfunc = function(){.....}; }if (typeof map !== 'undefined' && map.getCenter) {
// code for both map and map.getCenter exists
} else {
// if they dont exist
}
This is the right way to check for existence of a function.. Calling the function to test its existence will result in an error.
UPDATE: Snippet updated.
!==), you may as well just write if (!map.getCenter).
Technically you should be testing if map is undefined, not map.getCenter(). You can't call a function on an undefined reference.
However, Google's own tutorial suggests that you invoke your JavaScript that accesses the API in a body.onload handler, so that you do not attempt to reference anything until all of the remote .js files are loaded - are you doing this? This would solve the problem permanently, rather than failing cleanly when your JavaScript executes prior to loading the API.
if (typeof map.getCenter !== 'undefined')
Won't throw an error.
So, better yet, if (typeof map.getCenter === 'function') map.getCenter();
I have been in the habit recently of using the typeof operator to test for things and types. It returns the type as a string which I think avoids some response type confusion.
if( typeof map.getCenter != 'undefined') ...
I'm not sure if it's more correct, but I find good results with this process.
There is now an optional chaining operator that does exactly this.
The optional chaining (?.) operator accesses an object's property or calls a function. If the object accessed or function called using this operator is undefined or null, the expression short circuits and evaluates to undefined instead of throwing an error.
const adventurer = {
name: 'Alice',
cat: {
name: 'Dinah'
}
};
const dogName = adventurer.dog?.name;
console.log(dogName);
// Expected output: undefined
console.log(adventurer.someNonExistentMethod?.());
// Expected output: undefined
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining
You should be testing whether map is undefined. In your current check your are still trying to execute the function call.
Assuming that map.getCenter() is always a function, it's sufficient to just use this check:
if (map.getCenter) {
var x = map.getCenter();
}
The worked solution for me is try and catch,
const stopPropagation = (e) => {
try {
e.stopPropagation();
} catch (err) {
console.log("error with stopPropagation: " + err.error);
}
}
const triggerClick = (e) => {
stopPropagation(e);
};
