javascript - 如何高效地编写 Javascript 代码

Question

我有一个游戏，每当用户的分数达到 5、10 或 15 时，它就会添加一个新敌人。我随机选择并打算稍后更改的数字。

我能够弄清楚每次玩家达到这些分数之一时如何添加新敌人，但我必须为每个新分数创建一个新的 bool 变量。如何在没有很多 bool 值的情况下以更智能的方式编写相同的代码？

素描.js

var addEnemyAt5= true; //boolean I have to create over and over
var addEnemyAt10 = true;
var addEnemyAt15 = true;
var score = 0;

if (score == 5 && enemyScore5) {
  console.log("new enemy at 5");
  addEnemyAt5 = false;

} else if (score == 10 && enemyScore10) {
  console.log("new enemy at 10");
  addEnemyAt10 = false;

} else if (score == 15 && enemyScore15) {
  console.log("new enemy at 15");
  addEnemyAt15 = false;
}

HUD.js

this.scoreUpdate = function() {
  score += 5;
}

Answer 1

您可以创建一个 lastScore 变量来跟踪何时考虑了对 score 的更改:

素描.js:

var lastScore = 0
var score = 0

if (score > lastScore) {
  if (score === 5) {
    console.log("new enemy at 5")
  } else if (score === 10) {
    console.log("new enemy at 10")
  } else if (score === 15) {
    console.log("new enemy at 15")
  }
  lastScore = score
}

HUD.js:

this.scoreUpdate = function() {
  score += 5
}

---

演示片段:

var lastScore = 0
var score = 0

setInterval(function SketchDotJS() {

  if (score > lastScore) {
    if (score === 5) {
      console.log("new enemy at 5")
    } else if (score === 10) {
      console.log("new enemy at 10")
    } else if (score === 15) {
      console.log("new enemy at 15")
    }
    lastScore = score
  }

}, 10)

;(function HUDDotJS() {

  this.scoreUpdate = function() {
    score += 5
  }

})()

<!-- Boilerplate code to get the demo to work -->
<button onclick="scoreUpdate()">Increase <var>score</var> by 5</button>
<pre><var>score</var> = <span id="score">0</span></pre>
<script>setInterval(function(e){score===+e.textContent||(e.textContent=score)},10,document.getElementById('score'))</script>