There is a potential for the object to be 'undefined' when calling the getItem method on the window's local storage

 if (window?.sessionStorage?.getItem('accessToken')?.length > 0) {
  this.navigateToApplication();
}

Encountering the following error:

Object is possibly 'undefined'.ts(2532)

Any suggestions on how to resolve this issue? I am attempting to retrieve the value with optional chaining here.

Answer №1

An improved error message would be beneficial in this scenario. The issue lies in the fact that when

window?.sessionStorage?.getItem('accessToken')?
returns undefined if the item is not present, your if comparison ends up being undefined | number > number, which poses a challenge from a type perspective.

To address this, you can simply remove the > 0 part since both undefined and 0 are considered falsy:

if (window?.sessionStorage?.getItem('accessToken')?.length) {
// Adjusted by removing `> 0`
    this.navigateToApplication();
}

Playground link

Alternatively, you can provide a default value using nullish coalescing (??):

if (window?.sessionStorage?.getItem('accessToken')?.length ?? 0 > 0) {
// Adjusted to include nullish coalescing
    this.navigateToApplication();
}

window?.sessionStorage?.getItem('accessToken')?.length ?? 0
will result in 0 when the item is not found, allowing for a valid number > number comparison that satisfies TypeScript.

Playground link

Answer №2

One issue to address is the possibility that

window.sessionStorage.getItem("accessToken")
could be null or undefined. It's important to verify its existence before proceeding.

  const accessToken = window.sessionStorage.getItem("accessToken");
  if (accessToken && accessToken?.length > 0) {
    this.handleAccessToken();
  }

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