If you encounter issues with the positioning being defined and accessed correctly, it may be due to a change in the context of the this keyword. The context of this can vary depending on how it is called. For instance, when invoked through an event, the scope of this will be either the window or the element that triggered the event. Here's an example:
export class GeoService {
public pos: any;
public getPosition() {
navigator.geolocation.getCurrentPosition((position) => {
this.pos = position;
});
}
}
let geo = new GeoService();
// When executed, `this` refers to the window
setTimeout(geo.getPosition, 1000);
// When executed, `this` refers to the DOM element
document.getElementById('myDiv').addEventListener('click', geo.getPosition);
To work around this issue, you can utilize an anonymous function to call the original method of the object:
// When executed, `this` refers to the window
setTimeout(() => { geo.getPosition(); }, 1000);
// When executed, `this` refers to the DOM element
document.getElementById('myDiv').addEventListener('click', () => { geo.getPosition(); });
Alternatively, you can define the getPosition method as a property of the GeoService class using a lambda function to ensure proper scoping:
export class GeoService {
public pos: any;
public getPosition = () => {
navigator.geolocation.getCurrentPosition((position) => {
this.pos = position;
});
}
}
However, note that this approach creates a new function each time the GeoService class is instantiated, resulting in multiple copies of the function rather than sharing a single memory space. This incurs additional memory costs.
We hope these solutions help resolve your issue.