JS - 对象构造方法答案

【问题标题】：JS - Object Constructor MethodsJS - 对象构造方法
【发布时间】：2018-04-29 09:47:35
【问题描述】：

我正在尝试制作一个包含团队积分的对象（如下所示，其中显示“this.update”）。当我运行该程序时，它似乎并没有给团队得分，而且似乎甚至没有评估两个团队的目标。

我希望 team1Points 和 team2Points 属性从 IF 语句（如上述一个）或另一种解决方案中派生出来，类似于两支球队平局 1 分，胜方 3 分，负方 0 分。

teamsArray = ["Blue Team", "Red Team"];

function match(team1Name, team2Name, team1Goals, team2Goals) {
  this.team1Name = team1Name;
  this.team1Goals = team1Goals;
  this.team2Name = team2Name;
  this.team2Goals = team2Goals;
  this.update = function() {
    if (team1Goals > team2Goals) {
      team1Points = 3;
      team2Points = 0;
    } else if (team2Goals > team1Goals) {
      team2Points = 3;
      team1Points = 0;
    } else if (team1Goals == team2Goals) {
      team1Points = 1;
      team2Points = 1;
    }
  };
  this.update();
}

testMatch();

function testMatch() {
  var match1 = new match(teamsArray[0], teamsArray[1], 2, 0);
  console.log(match1);
}

【问题讨论】：

试试this.team1Points = 0等

标签： javascript object methods

【解决方案1】：

您的方法创建了全局变量而不是属性，而您甚至从未调用过它！

为了避免此类问题，我建议切换到现代 JavaScript 语法。以指令'use strict'; 开始您的脚本以启用严格模式并使用let 而不是var 定义变量。如果这样做，浏览器将不允许您在函数中定义全局变量。

至于你的代码的解决方案：

function match(team1Name, team2Name, team1Goals, team2Goals) {
  this.team1Name = team1Name;
  this.team1Goals = team1Goals;
  this.team2Name = team2Name;
  this.team2Goals = team2Goals;
  this.team1Points = this.team2Points = 0;

  this.update = function() {
    if (this.team1Goals > this.team2Goals) {
      this.team1Points = 3;
      this.team2Points = 0;
    } else if (this.team2Goals > this.team1Goals) {
      this.team2Points = 3;
      this.team1Points = 0;
    } else if (this.team1Goals == this.team2Goals) {
      this.team1Points = 1;
      this.team2Points = 1;
    }
  };
}

别忘了给.update()打电话。

m = new match("Alpha", "Beta", 0, 2);
m.update();

console.log("Team " + m.team1Name + " has " + m.team1Points + " points.");
console.log("Team " + m.team2Name + " has " + m.team2Points + " points.");

【讨论】：

哇，抱歉，如果您注意到那可怕的编辑序列。我对 SO 的使用有点生疏了。
我忘了添加 team1Points 和 team2Points 变量，但它并没有真正回答我的问题。我试图做 console.log(testMatch.update()) 并没有真正解决问题。我正试图让 team1Points = 3，因为他们进了更多的球。也许我不确定调用 update() 函数是错误的
更新函数不返回任何内容，因此不会记录其结果。如果要检查变量的值，则需要自己记录变量。
@Jay 我编辑了答案，并举例说明了如何创建匹配并记录结果。
啊，明白了。我也忘了在条件中添加this.。

【解决方案2】：

teamsArray = ["Blue Team", "Red Team"];

function match(team1Name, team2Name, team1Goals, team2Goals) {
  this.team1Name = team1Name;
  this.team1Goals = team1Goals;
  this.team2Name = team2Name;
  this.team2Goals = team2Goals;
  this.update = function() {
    if (team1Goals > team2Goals) {
      this.team1Points = 3;
      this.team2Points = 0;
    } else if (team2Goals > team1Goals) {
      this.team2Points = 3;
      this.team1Points = 0;
    } else if (team1Goals == team2Goals) {
      this.team1Points = 1;
      this.team2Points = 1;
    }
  };
  this.update();
}

testMatch();

function testMatch() {
  var match1 = new match(teamsArray[0], teamsArray[1], 2, 0);
  console.log(match1);
}

【讨论】：

【解决方案3】：

teamsArray = ["Blue Team", "Red Team"];

function match(team1Name, team2Name, team1Goals, team2Goals) {
  this.team1Name = team1Name;
  this.team1Goals = team1Goals;
  this.team2Name = team2Name;
  this.team2Goals = team2Goals;
  this.update = function() {
    if (team1Goals > team2Goals) {
      team1Points = 3;
      team2Points = 0;
      return "team1 win"
    } else if (team2Goals > team1Goals) {
      team2Points = 3;
      team1Points = 0;
      return "team2 win"
    } else if (team1Goals == team2Goals) {
      team1Points = 1;
      team2Points = 1;
      return "draw"
    }
  };
}

testMatch();

function testMatch() {
  var match1 = new match(teamsArray[0], teamsArray[1], 2, 0);

  console.log(match1.update());
}

【讨论】：