javascript - 如果未定义，如何将本地存储设置为 0？

Question

if localStorage["BestScore"] = undefined;
{
localStorage["BestScore"]=0; 
maxScore=0;
}

 var maxScore=localStorage["BestScore"]; 
  var newScore=false
  function drawScore(score) {
    if (newScore == true && score < maxScore) {
      newScore = false;
    }
    if (score > maxScore) {
      newScore = true;
      localStorage["BestScore"] = score;
      if ([5, 10, 15, 20].indexOf(score) !== -1) {
        play(sndMedal);
      } else { 
        play(sndGain);
      }
    }

This code is to set the max score and then store it but it doesn't seem to set the local storage to 0 if undefined.

Answer 1

if localStorage["BestScore"] = undefined;

应该是:

if( typeof localStorage["BestScore"] === 'undefined' )