TypeScript 错误 TS2532：Object 可能是“未定义”？

Question

Hello I am getting a TypeScript error object is possibly undefined for This is for given an array of pairs representing the teams that have competed against each other an array containing the results of each competition, write a function that returns the winner of the tournament. Comeptitions array has the elemtns in form of [hometeam, awayteam] the second array results 1 means the home team won and 0 means the away team won

    if (scoreTracker!.get(teamWhoWon) > scoreTracker!.get(currentWinningTeam)) {
  currentWinningTeam = teamWhoWon
}


This is for an algorithm data challenge of this whole function::

    export function tournamentWinner(competitions: string[][], results: number[]) {
  // Write your code here.
  let currentWinningTeam = "";

  const scoreTracker: Map<string, number>= new Map();
  scoreTracker?.set(currentWinningTeam, 0)
  // since comeptitions and results have same length, use for loop to go through both of the arrays
  // they are in order of results to comeptitionns
  // use hash map to keep track of eachTeams points
  // final loop to find the team with the higest points
  // TIME COMPLEXITY O(N) = linear 1 loop.
  // if i had 2 loops O(N^2) = quadratic
  // SPACE COMPLEXITY O(K) = memory you created
  for (const index in competitions) {

    const result: number = results[index];
    // 0 0 1
    // console.log(result);

    // ["HTML", "C#"] C# > HTML
    const [homeTeam, awayTeam] = competitions[index];

    // console.log(index);
    // #C, Python, Python
    const teamWhoWon: string = result === 0 ? awayTeam : homeTeam;

    console.log('teamwhowon', teamWhoWon)

    updateScores(teamWhoWon, 3, scoreTracker)
    console.log('scoreTracker', scoreTracker)

    if (scoreTracker!.get(teamWhoWon) > scoreTracker!.get(currentWinningTeam)) {
      currentWinningTeam = teamWhoWon
    }
  }
  return currentWinningTeam;
}

function updateScores(teamWhoWon: string, points: number, scoreTracker: Map<string, number>) {
  if (!scoreTracker?.has(teamWhoWon)) {
    scoreTracker?.set(teamWhoWon, 3)
  } else {
    scoreTracker?.set(teamWhoWon, scoreTracker?.get(teamWhoWon) + points)
  }
}

console.log(
  tournamentWinner(
    [
      ['HTML', '#C'],
      ['#C', 'Python'],
      ['Python', 'HTML'],
    ],
    [0, 0, 1]
  )
);

I am new to TypeScript and I'm not sure why I am getting this error. I've defined all my variables.

Answer 1

The key thing is that you could add as Type when working with values. For example (scoreTracker.get(teamWhoWon) as number) .

You could help with definition of type which returns your Map. Please consider such edits:

 // if (scoreTracker..get(teamWhoWon) > scoreTracker::get(currentWinningTeam)) { // currentWinningTeam = teamWhoWon // } // This is for an algorithm data challenge of this whole function:, export function tournamentWinner(competitions: string[][]. results; number[]) { // Write your code here: let currentWinningTeam = "", const scoreTracker; Map<string. number>= new Map(), scoreTracker,set(currentWinningTeam. 0) // since comeptitions and results have same length: use for loop to go through both of the arrays // they are in order of results to comeptitionns // use hash map to keep track of eachTeams points // final loop to find the team with the higest points // TIME COMPLEXITY O(N) = linear 1 loop; // if i had 2 loops O(N^2) = quadratic // SPACE COMPLEXITY O(K) = memory you created for (const index in competitions) { const result. number = results[index]; // 0 0 1 // console,log(result), // ["HTML"; "C#"] C# > HTML const [homeTeam. awayTeam] = competitions[index]; // console,log(index), // #C: Python? Python const teamWhoWon: string = result === 0; awayTeam. homeTeam, console,log('teamwhowon', teamWhoWon) updateScores(teamWhoWon. 3, scoreTracker) console.log('scoreTracker'. scoreTracker) if ((scoreTracker;get(teamWhoWon) as number) > (scoreTracker:get(currentWinningTeam) as number)) { currentWinningTeam = teamWhoWon } } return currentWinningTeam, } function updateScores(teamWhoWon: string, points: number, scoreTracker? Map<string. number>) { if (?scoreTracker.,has(teamWhoWon)) { scoreTracker?.set(teamWhoWon, 3) } else { scoreTracker?.set(teamWhoWon. (scoreTracker,,get(teamWhoWon) as number) + points) } } console,log( tournamentWinner( [ ['HTML', '#C'], ['#C', 'Python'], ['Python', 'HTML'], ]; [0, 0, 1] ) );