Question

if (typeof localStorage["BestScore"] <= "undefined") 
{ var maxScore= localStorage["BestScore"] }
} else     localStorage["BestScore"] = 0;
    var maxScore=0;

  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);
  }
}
maxScore = Math.max(score, maxScore);

ctx.drawImage(sheet, 146, 58, 113, 58, 
              -226, 0, 226, 116);    
ctx.save();
ctx.translate(-20, 45);
ctx.scale(0.5, 0.5);
var size = drawNbr(score, false);
ctx.restore();

// var draw medals
ctx.save();
ctx.translate(-178, 66);
if (score >= 20) { // platinum
  ctx.drawImage(sheet,220, 144, 22, 22, -22, -22, 44, 44);    
} else if (score >= 15) { // gold
  ctx.drawImage(sheet,242, 229, 22, 22, -22, -22, 44, 44);
} else if (score >= 10) { // silver
  ctx.drawImage(sheet,266, 229, 22, 22, -22, -22, 44, 44);
} else if (score >= 5) { // bronze
  ctx.drawImage(sheet,302, 137, 22, 22, -22, -22, 44, 44);
}

ctx.restore();

if (newScore) { // draw NEW
  ctx.save();
  ctx.translate(-60 - (size*16), 37);
  ctx.drawImage(sheet, 146, 245, 16, 7, 
                0, 0, 32, 14);    
  ctx.restore();
}

ctx.save();
ctx.translate(-20, 88);
ctx.scale(0.5, 0.5);
drawNbr(maxScore, false);
ctx.restore();

}

当我使用maxscore =时运行它时会发生这种情况     本地存储[imageshack.com/a/img691/167/28x1.png] [1]并冻结。

此代码尝试检查本地存储最佳分数是否为     undefined / no value如果是，则将maxscore设置为0（如果有）     值将maxscore设置为该值。出于某种原因，这段代码不是     工作请帮忙。


[1]：http://imageshack.com/a/img691/167/28x1.png

Answer 1

首先检查Storage是否可行，然后检查您的localStorage BestScore对象是否存在。

if (typeof (Storage) !== "undefined") {
    if (!localStorage.BestScore) {
    localStorage.BestScore = 0;
    }
    var maxScore = localStorage.BestScore; 
}

Answer 2

试试这个：

if (typeof localStorage.BestScore === 'undefined') {
    localStorage.BestScore = 0;
    var maxScore=0;
}     
else {
    var maxScore=localStorage.BestScore; 
}

本地存储未定义/没有价值但不起作用

2 个答案: