ts2322 error in Typescript explained

If you've been working with Typescript, you may have come across the ts2322 error. This error occurs when you try to assign a value of one type to a variable of another incompatible type. The error message will usually look something like this:

error TS2322: Type 'string' is not assignable to type 'number'.

This error can be frustrating to deal with, especially if you're not sure how to fix it. In this blog post, we'll look at some examples of the ts2322 error and how to solve them.

Examples of ts2322 Errors and Solutions

Example 1: Assigning a String to a Number

Let's say we have the following Typescript code:

let x: number = 10; 
x = "hello";

This code will result in a ts2322 error, since we're trying to assign a string value to a variable of type number. To fix this, we can either change the type of the variable to string, or assign a number value to the variable:

let x: string = "hello"; // OR let x: number = 10; x = 5;

Example 2: Incorrect Return Type

Another common scenario where the ts2322 error can occur is when a function returns a value of a different type than the one specified in the function's return type. Consider the following code:

function multiply(a: number, b: number): string {
  return a * b;
}

This code will result in a ts2322 error, since the function is declared to return a string but is actually returning a number. To fix this, we can either change the return type to number or ensure that the function returns a string value:

function multiply(a: number, b: number): number {
  return a * b;
}
// OR
function multiply(a: number, b: number): string {
  return (a * b).toString();
}

Example 3: Incompatible Object Types

The ts2322 error can also occur when trying to assign an object of one type to a variable of a different incompatible type. Consider the following code:

interface Person {
  name: string;
  age: number;
}
let john: Person = {
  name: "John",
  age: 30,
};

let alice: { name: string } = john;

This code will result in a ts2322 error, since we're trying to assign an object of type Person to a variable of type { name: string }. To fix this, we can either change the type of the variable to Person, or ensure that the object being assigned only has the required properties:

interface Person {
  name: string;
  age: number;
}
let john: Person = {
name: "John",
age: 30,
};

let alice: { name: string, age?: number } = john;

In this example, we added an optional age property to the variable alice to match the structure of the Person object.