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JavaScript

saul bard
saul bard
7,581 Points
Posted by saul bard
saul bard
7,581 Points

Why isn't my balance changing?

Can someone please have a look at why my balance isn't changing? I made it so that the due date is set in the past. I also added an event listener so when I click on the page it runs chargeFines() but the balance of the patron is not changing.

https://w.trhou.se/bc7f9gnp4v

Thanks

1 Answer

Steven Parker
Steven Parker
231,210 Points
Steven Parker
Steven Parker
231,210 Points

The "filter" function in "chargeFines" does not return a value, so the filtered list ("latePatrons") is always empty.

You can return a value explicitly with a "return" statement, or you can use the abbreviated form of arrow function and the result of evaluating the expression will be implicitly returned:

// this filter function does not return anything
patron => { (patron.currentBook !==null && patron.currentBook.dueDate < today) }
// but this one will
patron => { return (patron.currentBook !==null && patron.currentBook.dueDate < today); }
// and so will this one
patron => (patron.currentBook !==null && patron.currentBook.dueDate < today)