array.prototype.map() 需要计算 NFL 球队的赢、输、平答案

【问题标题】：array.prototype.map() Need to Calculate Won, Lost, Tied for NFL Teamarray.prototype.map() 需要计算 NFL 球队的赢、输、平
【发布时间】：2020-02-06 15:56:04
【问题描述】：

我正在试验 .map() 数组方法，但找不到在我的对象中生成“wlt”列的正确语法。 “wlt” 代表 Win、Loss 或 Tie。

目前我正在使用以下代码生成“wlt”列：

    const scores = philadephiaEaglesScores.map(function(item){
    const obj = {
    "weekNumber": item.weekNumber, 
    "name": item.ourName, 
    "oppName": item.oppName, 
    "ourScore": item.ourScore,
    "oppScore":  item.oppScore,
    "wlt": item.ourScore - item.oppScore
    }
    return obj;
    });

这确实有效，如果我们赢了比赛，给我一个正数，如果我们输了比赛，则给我一个负数，如果比赛是平局，则给我 0。

我想更进一步，在第一个代码示例中实际生成一个字符串值 Won、Lost 或 Tie。

我可以使用以下代码使其工作，但无法让第二个代码示例在第一个代码示例中工作。

    let winLossTie = philadephiaEaglesScores.map(item => {
    if (item.ourScore > item.oppScore) {
    return "W";
    } if (item.ourScore < item.oppScore) {
    return "L";
    } else {return "T"}
    });

My JSON data is listed below:
    const philadephiaEaglesScores = [
    {"weekNumber": "1","ourName": "Philadephia Eagles", "oppName": "Redskins", "ourScore": "32", 
    "oppScore": "27", "location": ""},
    {"weekNumber": "2","ourName": "Philadephia Eagles", "oppName": "Falcons", "ourScore": "20", 
    "oppScore": "27", "location": ""},
    {"weekNumber": "3","ourName": "Philadephia Eagles", "oppName": "Lions", "ourScore": "24", "oppScore": 
    "27", "location": ""},
    {"weekNumber": "4","ourName": "Philadephia Eagles", "oppName": "Packers", "ourScore": "34", 
    "oppScore": "27", "location": ""},
    {"weekNumber": "5","ourName": "Philadephia Eagles", "oppName": "Packers", "ourScore": "31", 
    "oppScore": "6", "location": ""},
    {"weekNumber": "6","ourName": "Philadephia Eagles", "oppName": "Vikings", "ourScore": "20", 
    "oppScore": "38", "location": ""},
    {"weekNumber": "7","ourName": "Philadephia Eagles", "oppName": "Cowboys", "ourScore": "10", 
    "oppScore": "37", "location": ""},
    {"weekNumber": "8","ourName": "Philadephia Eagles", "oppName": "Bills", "ourScore": "31", "oppScore": 
    "13", "location": ""},
    {"weekNumber": "9","ourName": "Philadephia Eagles", "oppName": "Bears", "ourScore": "22", "oppScore": 
    "14", "location": ""},
    {"weekNumber": "11","ourName": "Philadephia Eagles", "oppName": "Patriots", "ourScore": "10", 
    "oppScore": "17", "location": ""},
    {"weekNumber": "12","ourName": "Philadephia Eagles", "oppName": "Seahawks", "ourScore": "9", 
    "oppScore": "17", "location": ""},
    {"weekNumber": "13","ourName": "Philadephia Eagles", "oppName": "Dolphins", "ourScore": "31", 
    "oppScore": "37", "location": ""},
    {"weekNumber": "14","ourName": "Philadephia Eagles", "oppName": "Giants", "ourScore": "23", 
    "oppScore": "17", "location": ""},
    {"weekNumber": "15","ourName": "Philadephia Eagles", "oppName": "Redskins", "ourScore": "37", 
    "oppScore": "27", "location": ""},
    {"weekNumber": "16","ourName": "Philadephia Eagles", "oppName": "Cowboys", "ourScore": "17", 
    "oppScore": "9", "location": ""},
    {"weekNumber": "17","ourName": "Philadephia Eagles", "oppName": "Giants", "ourScore": "37", 
    "oppScore": "17", "location": ""},
    ];

【问题讨论】：

标签： javascript array.prototype.map

【解决方案1】：

在第一个代码中，更改：

"wlt": item.ourScore - item.oppScore

到：

"wlt": "LTW"[1+Math.sign(item.ourScore - item.oppScore)]

您实际上不能使用迭代整个数组的第二个函数。如果该函数将数组中的 one 对象作为参数，并且仅返回适用于该对象的字符串，则它将起作用。然后你可以像这样调用那个函数：

"wlt": winLossTie(item)

所以，为了清楚起见，函数需要更改为以下内容：

function winLossTie(item) {
  if (item.ourScore > item.oppScore) {
    return "W";
  } if (item.ourScore < item.oppScore) {
    return "L";
  } else {
    return "T"
  }
});

但是使用 Math.sign（返回 -1、0 或 1）的快捷方式使其足够短，根本不需要单独的函数。

【讨论】：

【解决方案2】：

您可以使用三元运算符替换 if/else 语句。

看起来像这样：

    const scores = philadephiaEaglesScores.map(function(item){
    const obj = {
    "weekNumber": item.weekNumber, 
    "name": item.ourName, 
    "oppName": item.oppName, 
    "ourScore": item.ourScore,
    "oppScore":  item.oppScore,
    "wlt": item.ourScore > item.oppScore ? "W" : item.ourScore < item.oppScore ? "L" : "T"
    }
    return obj;
    });

您可能希望将三元与语句/表达式/函数分开以获得更简洁的代码。

【讨论】：