This is part of my series on Typescript Learnings, where I share micro posts about everything I'm learning related to Typescript.
And it was first published at TK's blog.
It's a common feature to destructure objects in JavaScript. For example, imagine we have a Person object. It looks like:
const person = {
firstName: 'TK',
age: 24,
email: 'tk@mail.com',
isLearning: true
};
And when we use it, sometimes we want to destructure the object to get the attributes.
const { firstName, age, email, isLearning } = person;
In Typescript, it works the same way. But with types. So let's type the attributes. At first I thought I could add the type after each attribute. Something like:
const { firstName: string, age: number, email: string, isLearning: boolean } = person;
But it actually doesn't compile that way. We don't specify a type for each attribute, we specify the object type. We could add this way:
const {
firstName,
age,
email,
isLearning
}: {
firstName: string,
age: number,
email: string,
isLearning: boolean
} = person;
Or we could have a Person type (or interface) to handle these types.
type Person = {
firstName: string,
age: number,
email: string,
isLearning: boolean
};
And use it in the object destructuring:
const { firstName, age, email, isLearning }: Person = person;
Implementing a type is cool because we could also use it in the person definition:
const person: Person = {
firstName: 'TK',
age: 24,
email: 'tk@mail.com',
isLearning: true
};
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