TS2531: Nullability detected in object when using .match() method

I'm encountering a linting error on fileNameMatches[0] in the following code snippet. Strangely, the error doesn't appear on the Boolean() check. Even if I remove that check, the issue remains unresolved. Can anyone suggest a solution?

protected getLocalFilename(): string {
  const fileNameMatches: string[] | null = this.filePath.match(/\/(.+\.js)$`/);
  
  if (Boolean(fileNameMatches) && fileNameMatches[0] !== null) { // TS2531: Object is possibly 'null'
    return fileNameMatches[0]; // TS2531: Object is possibly 'null'
  } else {
    throw Error("No filename found during regex matching");
  }
}

Another Attempt:

if (typeOf fileNameMatches !== "null") {

The above test also triggers the "Object is possibly 'null'" warning.

Answer №1

Resolved by implementing the use of the ! operator to ensure that fileNameMatches![0] is not null:

function retrieveFileName(): string {
  const fileNameMatches: string[] | null = this.filePath.match(/\/(.+\.js)$`/);
  
  if (Boolean(fileNameMatches)) { 
    return fileNameMatches![0];
  }
  else {
    throw Error("No filename was found during regex matching");
  }
}

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