-
WEBSITE
Does Typescript support the ?. operator? (And, what's it called?)
As of TypeScript 3.7 (released on November 5, 2019), this feature is supported and is called Optional Chaining: At its core, optional chaining lets us write code where TypeScript can immediately stop running some expressions if we run into a null or undefined.
Do more...
Share, comment, bookmark or report
-
WEBSITE
Typescript input onchange event.target.value - Stack Overflow
This is a great answer that works across the board. I was heavy on Angular, was forced onto React for a year, and am now playing with Angular again to stay fresh on it. React provides some really nice event interfaces that Typescript natively lacks. This approach helps get the same desired typing, even in vanilla. Thanks. –
Do more...
Share, comment, bookmark or report
-
WEBSITE
What does the ampersand (&) mean in a TypeScript type definition?
"Intersection" refers to the resulting type, not the operation performed on the properties.An object belonging to both Type A and Type B must have all properties in A (so that it is an instance of A) while also having all the properties of B (so that it is also an instance of B).
Do more...
Share, comment, bookmark or report
-
WEBSITE
Why use triple-equal (===) in TypeScript? - Stack Overflow
JavaScript as the target of compilation (TypeScript design goal 4) All TypeScript must be representable in JavaScript. Further, it should be idiomatic JavaScript where possible. Really though, the TypeScript compiler could use methods returning booleans for all comparisons, doing away with == and === entirely.
Do more...
Share, comment, bookmark or report
-
WEBSITE
What is TypeScript and why should I use it instead of JavaScript ...
TypeScript is a superset of the JavaScript language that has a single open-source compiler and is developed mainly by a single vendor: Microsoft. The goal of TypeScript is to help catch mistakes early through a type system and to make JavaScript development more efficient. Essentially TypeScript achieves its goals in three ways:
Do more...
Share, comment, bookmark or report
-
WEBSITE
How to convert a string to number in TypeScript?
In Typescript we convert a string to a number in the following ways: parseInt() : This function takes 2 arguments, the first is a string to parse. The second is the radix (the base in mathematical numeral systems, e.g. 10 for decimal and 2 for binary).
Do more...
Share, comment, bookmark or report
-
WEBSITE
Is key-value pair available in TypeScript? - Stack Overflow
KeyValue interface exists in angular library that uses typescript. So you have this generic interface to use if your project is angular. Or you can use its declaration to get a nice generic KeyValue interface if you are not using TS in angular. export declare interface KeyValue<K, V> { key: K; value: V; }
Do more...
Share, comment, bookmark or report
-
WEBSITE
How do I dynamically assign properties to an object in TypeScript ...
TypeScript is used to catch (potential) errors at compile time. If you cast to any to mute errors then you lose the power of typing and may as well go back to pure JS. any should ideally only be used if you're importing code for which you cannot write TS definitions or whilst migrating your code from JS to TS
Do more...
Share, comment, bookmark or report
-
WEBSITE
In TypeScript, what is the ! (exclamation mark / bang) operator when ...
It is explained in the TypeScript release notes: A new ! post-fix expression operator may be used to assert that its operand is non-null and non-undefined in contexts where the type checker is unable to conclude that fact.
Do more...
Share, comment, bookmark or report
-
WEBSITE
What does the `is` keyword do in typescript? - Stack Overflow
Typescript needs to know that the function into which you pass an object is functioning like a type guard. If it just returns type true or false, how can Typescript know that it's indeed a type guard and not just some arbitrary function that returns true if the object is truthy.
Do more...
Share, comment, bookmark or report
Comments