How can I write a date using typescript?

Question

I select a date in the picker, and try to write it in the state, but I get an error, how to do it correctly?

const [dateFrom, setDateFrom] = useState<Date | null>(new Date());

onChange={(e, v) => {
  setDateFrom(v);
}}

ype '(e: Date | null, v: Date | null) => void' is not assignable to type '(date: Date | null, value?: string | null | undefined) => void'. Types of parameters 'v' and 'value' are incompatible. Type 'string | null | undefined' is not assignable to type 'Date | null'. Type 'undefined' is not assignable to type 'Date | null'.

gbalduzzi · Accepted Answer · 2020-08-26 13:40:44Z

1

The error tells you that you are not doing the proper checks on the value:

Type 'string | null | undefined' is not assignable to type 'Date | null'. Type 'undefined' is not assignable to type 'Date | null'.

v could be string, null, undefined and you are assigning it to a variable that is Date or null. They are not compatible types.

You should ~~cast~~ create a Date in case v is a string, or assign null otherwise

onChange={(e, v) => {
 setDateFrom(typeof v === 'string' ? new Date(v) : null);
}}

edited Aug 26, 2020 at 13:40

answered Aug 26, 2020 at 9:44

gbalduzzi

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Comments

arslan2012 · Accepted Answer · 2020-08-26 09:38:38Z

0

const [dateFrom, setDateFrom] = useState<Date | undefined>(new Date());

onChange={(e, v) => {
  setDateFrom(new Date(v));
}}

answered Aug 26, 2020 at 9:38

arslan2012

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