试图让警报显示出来

Question

我正在尝试使用一个警告框来打印存储在阵列中的温度，具体取决于星期几（0-6），但没有发生任何事情。

我哪里错了？

码：

var highTemps = ["32", "41", "36", "29", "39", "37", "40"];
var lowTemps = ["18", "24", "20", "27", "30", "31", "27"];


    var d = new Date();
    var n = d.getDay();


    if(n == 0){
        alert("Expect a high of " highTemps[0] " and a low of " lowTemps[0] " today.");

    }else if(n == 1){
       alert ("Expect a high of" highTemps[1] "and a low of" lowTemps[1] "today.");

    }else if(n == 2){
       alert("Expect a high of" highTemps[2] "and a low of" lowTemps[2] "today.");

    }else if(n == 3){
       alert("Expect a high of" highTemps[3] "and a low of" lowTemps[3] "today.");

    }else if(n == 4){
       alert("Expect a high of" highTemps[4] "and a low of" lowTemps[4] "today.");

    }else if(n == 5){
       alert("Expect a high of" highTemps[5] "and a low of" lowTemps[5] "today.");

    }else if(n == 6){
       alert("Expect a high of" highTemps[6] "and a low of" lowTemps[6] "today.");

    }else {
        alert("Who knows what the temperature is?!");
    };


    console.log("The average temperature for this week is [average].");
    console.log("The warmest day of the week will have a high temperature of [hTemperature]");
    console.log("The lowest low temperature of the week will be [lTemperature].)");

Answer 1

您的问题是您需要使用+运算符将消息的静态部分与动态部分连接起来：

var highTemps = ["32", "41", "36", "29", "39", "37", "40"];
var lowTemps = ["18", "24", "20", "27", "30", "31", "27"];

var d = new Date();
var n = d.getDay();

if(n == 0){
  alert("Expect a high of " + highTemps[0] + " and a low of " + lowTemps[0] + " today.");
}else if(n == 1){
  alert ("Expect a high of" + highTemps[1] + "and a low of" + lowTemps[1] + "today.");
}else if(n == 2){
  alert("Expect a high of" + highTemps[2] + "and a low of" + lowTemps[2] + "today.");
}else if(n == 3){
  alert("Expect a high of" + highTemps[3] + "and a low of" + lowTemps[3] + "today.");
}else if(n == 4){
  alert("Expect a high of" + highTemps[4] + "and a low of" + lowTemps[4] + "today.");
}else if(n == 5){
  alert("Expect a high of" + highTemps[5] + "and a low of" + lowTemps[5] + "today.");
}else if(n == 6){
  alert("Expect a high of" + highTemps[6] + "and a low of" + lowTemps[6] + "today.");
}else {
  alert("Who knows what the temperature is?!");
};

console.log("The average temperature for this week is [average].");
console.log("The warmest day of the week will have a high temperature of [hTemperature]");
console.log("The lowest low temperature of the week will be [lTemperature].)");

现在，说了这么多，我们可以通过使用n变量作为数组的索引来简化你的代码，并摆脱所有if/then。

另外，使用if / then的类型你有一个switch语句可以更简洁：

var highTemps = ["32", "41", "36", "29", "39", "37", "40"];
var lowTemps = ["18", "24", "20", "27", "30", "31", "27"];

var d = new Date();
var n = d.getDay();

// If the array contains an index of the current day number
if(highTemps.indexOf(n) > -1){
  // Just extract that element from the arrays and use it.
  alert("Expect a high of " + highTemps[n] + " and a low of " + lowTemps[n] + " today.");
} else {
  // Otherwise, show the default message
  alert("Who knows what the temperature is?!");
}

console.log("The average temperature for this week is [average].");
console.log("The warmest day of the week will have a high temperature of [hTemperature]");
console.log("The lowest low temperature of the week will be [lTemperature].)");

Answer 2

警报功能有问题。字符串消息应使用'+'附加数组值。

<script>
var highTemps = ["32", "41", "36", "29", "39", "37", "40"];
var lowTemps = ["18", "24", "20", "27", "30", "31", "27"];
var d = new Date();
var n = d.getDay();

if(n == 0){ 
   alert("Expect a high of " + highTemps[0] +" and a low of " +lowTemps[0] + " today.");

}else if(n == 1){
   alert ("Expect a high of" + highTemps[1] + "and a low of" +lowTemps[1] + "today.");

}else if(n == 2){
   alert("Expect a high of" + highTemps[2] + "and a low of" + lowTemps[2] + "today.");

}else if(n == 3){
   alert("Expect a high of" + highTemps[3] + "and a low of" + lowTemps[3] + "today.");

}else if(n == 4){
   alert("Expect a high of" + highTemps[4] + "and a low of" +lowTemps[4]+ "today.");

}else if(n == 5){
   alert("Expect a high of" + highTemps[5] + "and a low of" + lowTemps[5] + "today.");

}else if(n == 6){
   alert("Expect a high of" + highTemps[6] + "and a low of" + lowTemps[6] + "today.");

}else {
    alert("Who knows what the temperature is?!");
};


console.log("The average temperature for this week is [average].");
console.log("The warmest day of the week will have a high temperature of [hTemperature]");
console.log("The lowest low temperature of the week will be [lTemperature].)");

Answer 3

我认为你的主要问题是window缺少window.alert，你也可以使用ES6语法来避免使用+：

const highTemps = ["32", "41", "36", "29", "39", "37", "40"];
const lowTemps = ["18", "24", "20", "27", "30", "31", "27"];
const d = new Date();
const n = d.getDay();

if(n === 0) {
  window.alert(`Expect a high of ${highTemps[0]} and a low of ${lowTemps[0]} today.`);
} else if(n === 1) {
  window.alert (`Expect a high of ${highTemps[1]} and a low of ${lowTemps[1]} today.`);
} else if(n === 2) {
  window.alert (`Expect a high of ${highTemps[2]} and a low of ${lowTemps[2]} today.`);
} else if(n === 3) {
  window.alert (`Expect a high of ${highTemps[3]} and a low of ${lowTemps[3]} today.`);
} else if(n === 4) {
  window.alert (`Expect a high of ${highTemps[4]} and a low of ${lowTemps[4]} today.`);
} else if(n === 5) {
  window.alert (`Expect a high of ${highTemps[5]} and a low of ${lowTemps[5]} today.`);
} else if(n === 6) {
  window.alert (`Expect a high of ${highTemps[6]} and a low of ${lowTemps[6]} today.`);
} else {
  alert("Who knows what the temperature is?!");
};


console.log("The average temperature for this week is [average].");
console.log("The warmest day of the week will have a high temperature of [hTemperature]");
console.log("The lowest low temperature of the week will be [lTemperature].)");

或者你甚至可以：

const highTemps = ["32", "41", "36", "29", "39", "37", "40"];
const lowTemps = ["18", "24", "20", "27", "30", "31", "27"];
const d = new Date();
const n = d.getDay();

for (let i = 0; i < highTemps.length; i++) {
  if  (n === i) {
    window.alert(`Expect a high of ${highTemps[i]} and a low of ${lowTemps[i]} today.`);  
  } 

  if (n >= 7) {
    window.alert("Who knows what the temperature is?!");
  }
}

console.log("The average temperature for this week is [average].");
console.log("The warmest day of the week will have a high temperature of [hTemperature]");
console.log("The lowest low temperature of the week will be [lTemperature].)");

Answer 4

除了以前的注释，您的代码以“</ script>”结尾。 “<”和“/”之间有一个空格。