Variable ‘test’ is used before being assigned – Typescript

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Variable ‘test’ is used before being assigned – Typescript

How to solve Variable ‘test’ is used before being assigned – Typescript

To clarify a little, this hinges on the difference between “assigned” and “defined.” For example:
let myDate: Date; // I've defined my variable as of `Date` type, but it still has no value. if (!someVariable) { myDate = new Date(); } console.log(`My date is ${myDate}`) // TS will throw an error, because, if the `if` statement doesn't run, `myDate` is defined, but not assigned (i.e., still has no actual value).
Defining simply means giving it an initial value:
let myDate: Date | undefined = undefined; // myDate is now equal to `undefined`, so whatever happens later, TS won't worry that it won't exist.

Variable ‘test’ is used before being assigned – Typescript

To clarify a little, this hinges on the difference between “assigned” and “defined.” For example:
let myDate: Date; // I've defined my variable as of `Date` type, but it still has no value. if (!someVariable) { myDate = new Date(); } console.log(`My date is ${myDate}`) // TS will throw an error, because, if the `if` statement doesn't run, `myDate` is defined, but not assigned (i.e., still has no actual value).
Defining simply means giving it an initial value:
let myDate: Date | undefined = undefined; // myDate is now equal to `undefined`, so whatever happens later, TS won't worry that it won't exist.

Solution 1

To clarify a little, this hinges on the difference between “assigned” and “defined.” For example:

let myDate: Date; // I've defined my variable as of `Date` type, but it still has no value.

if (!someVariable) {
   myDate = new Date();
}

console.log(`My date is ${myDate}`) // TS will throw an error, because, if the `if` statement doesn't run, `myDate` is defined, but not assigned (i.e., still has no actual value).
   

Defining simply means giving it an initial value:

let myDate: Date | undefined = undefined; // myDate is now equal to `undefined`, so whatever happens later, TS won't worry that it won't exist.

Original Author Andrew Of This Content

Solution 2

let test!: A;

add a ‘!’ after variable name

see: typescript/playground

Original Author princekin Of This Content

Solution 3

It is indeed unassigned. It is defined, but it has no value.

In my humble opinion, the cleanest way would be to return a literal:

const modifyData = (g: B):A => {
    return {
        name: g.name['ru'],
        age: g.age,
        sex: g.sex
    } as A;
};

Original Author mleko Of This Content

Conclusion

So This is all About This Tutorial. Hope This Tutorial Helped You. Thank You.

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