Angular中如何将() => number类型转换为number类型？

Hey there! Let's break down this error and fix it quickly.

The error message tells you exactly what's wrong: g.lat isn't a plain number—it's a function that returns a number (that's what () => number means). When you try to assign the function itself to your lat: number variable, TypeScript throws a fit because they're different types.

Here are the solutions to get this working: #

1. Call the function to get its return value (most common fix)

Since g.lat is a function that produces a number, just add parentheses to execute it and grab the result:

for (let g of parcelData.geom){ 
  const point = []; 
  let lat : number; 
  lat = g.lat(); // Add parentheses to call the function
  // Rest of your logic...
}

This works because g.lat() runs the function and returns a number, which matches the type you declared for lat.

2. Double-check your type definitions (if this is unexpected)

If you were expecting g.lat to be a number (not a function), you might have a mistake in how you've typed parcelData.geom. For example, if you have an interface for the geometry objects, make sure it's defined correctly:

// Wrong: lat is a function
interface GeometryItem {
  lat: () => number;
}

// Correct: lat is a number
interface GeometryItem {
  lat: number;
}

Updating the interface to reflect the actual data structure will resolve the error without changing your assignment code.

3. Add a type guard for safety (if the type is uncertain)

If there's a chance g.lat could sometimes be a number and sometimes a function, use a type guard to handle both cases safely:

for (let g of parcelData.geom){ 
  const point = []; 
  let lat : number; 

  if (typeof g.lat === 'function') {
    lat = g.lat();
  } else {
    lat = g.lat;
  }
  // Rest of your logic...
}

This ensures you handle both scenarios without TypeScript errors.

内容的提问来源于stack exchange，提问作者obar