Getting Object is possibly 'null' even after null checking-CodePudding

export async function getSingleUserQA(command: Command, period?: string[]) {
  let slackUserID;

  if (command && command.text) {
    slackUserID = command.text.match("/(?<=@)(.*?)(?=|)/g")[0];
  }
}

I am being flagged that 'command' is possibly 'null' or 'undefined'. How come if I am making sure that command exists and command.text exists?

CodePudding user response：

Look closely at the warning. It's not saying that command might not exist, but that this whole expression:

command.text.match("/(?<=@)(.*?)(?=|)/g")

might not.

What do you want to do if the regular expression has no match? Figure that out, and guard it appropriately.

if (command && command.text) {
    const match = command.text.match("/(?<=@)(.*?)(?=|)/g");
    if (match) {
        slackUserID = match[0];
    } else {
        // handle badly formatted command
    }
}

You should also probably do

let slackUserID: string;

or only use the result inside the conditional.