According to my experience, When learning new technology or concepts, Reading articles in English is better than Korean ones. Because most of the technical terms came from English. I have some experiences that I was confused about terms which I’ve already learned in Korean. Because It does not match English terms. After that, I’ve decided I should be familiar with English terms.
Today I want to get deep insights into Type Assertion and Type Casting in Typescript.
What is Type Assertion?
Type Assertion is let Typescript compiler know that ‘I know what type is it for this variable.’. It’s done by declaring forced Type. E.g
interface Foo {
bar: number;
bas: string;
}
var foo = {} as Foo;
foo.bar = 123;
foo.bas = 'hello';
Originally the syntax for is <Foo> but, It conflicts with JSX syntax. so We can use as Foo as well with tsx files.
It’s different from Casting. Because Casting is generally runtime operation. But Type Assertion is compile time operation to provide hint to compiler.
What is Type Casting?
In Typescript, Type Casting is not used.