The possibilities are endless when combining user-defined type guards, template literal strings, and nominal typings. toString() method to convert it on string date format. First, we will create sample new date() object variable, after then, we will use. toString() to convert date to string date. Remember that this approach is also applicable to other custom strings, like custom user-ids, user-XXXX, and other date strings, like YYYY-MM-DD. 3 Answers Sorted by: 0 If all such strings have the exact same format, you can split them as such (and assuming your format is YYYYMMDD): let dateStr '20200408' let year dateStr.slice (0,4) let month dateStr.slice (4, 6) let day dateStr. Today, we are going to learn How to convert date to date string format in typescript, here we will use built-in method. I hope this article shed some light on what TypeScript is capable of in the context of typing custom strings. Throws Error: Invalid date string: 19990231 valid string format, invalid date (February doenst have 31 days) Type error: Argument of type '"asdf"' is not assignable to parameter of type '"19000101" |. This may sound a little abstract, so let’s see it in action: type Person = 'Jeff' | 'Maria' The type template literals resolve to a union of all the string combinations for a given template. Introduced in TypeScript v4.1, template literal types share the syntax with JavaScript template literals but are used as types. Let’s get started! Table of contentsīefore we jump into the code, let’s briefly review the TypeScript features we’ll leverage to achieve our goal, template literal types and narrowing through type predicates. In this article, I’ll take you through my approach for improving the developer experience and reducing potential bugs by typing those date strings. For example, const dog = 'alfie' is also inferred as a string type. While this isn’t technically wrong, working with such a type definition is broad, making it tough to work effectively with those date strings. date-fns always returns a date in the same time zone, no matter whats passed - a timestamp, a string or a date. Since those dates are string variables, TypeScript infers the string type by default. date-fns supports both TypeScript and Flow. In one of my recent projects, I had to deal with multiple custom representations of dates as strings, like YYYY-MM-DD and YYYYMMDD. Alain Perkaz Follow A passionate and disciplined software engineer.
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