Question

我多年来一直在做一个简单的DOM游戏。而且我无法弄清楚范围为何如此。解释在下面的代码中。我不明白为什么必须在if语句中的函数内部声明一个var才能起作用，而不是全局范围。我现在已经处理了好几个小时，我知道它一定很简单，但是现在它让我发疯。

//this code does not work - if the var currentScore is declared in the global scope

var
    activePlayer = 1;
    btnRoll = document.querySelector(".btn-roll");
    diceImage = document.querySelector(".dice");
    diceImage.style.display="none";

//var currentScore selects a div - either the one from player 1 or 2

    currentScore = document.querySelector("#current-" + activePlayer);


    btnRoll.addEventListener ("click", function(){
        //after clicking roll dice - generate random num
        var diceNum = Math.floor(Math.random() * 6) + 1;
        diceImage.style.display="block";
        //view a correct image that is the generated number
        diceImage.src="dice-" + diceNum + ".png";
        //if the rolled number greater than one - add to the roundScore
        if (diceNum !== 1) {
            roundScore += diceNum;
//this below should change the text of 0 of a div for player 1 to text of the round score -which it does
            currentScore.textContent = roundScore;


        }
        //else its other players round
        else {
            roundScore = 0;
           if(activePlayer === 1) {
               activePlayer = 2;
  //when I console.log the active player it changes to 2

           }
           else {
               activePlayer = 1;


           }
        }

    });
//problem comes when its suppose to start again - it does recognize that its player 2 but the currentScore variable is stil #current-1 instead of #current-2.

要使其正常工作，currentScore var必须以相同的方式声明，但不能在全局范围内声明，而应在第一个if语句中声明。为什么？

函数内的if语句-与全局范围的关系

0 个答案: