Question

我正在为一个学校作业制作一个简单的javascript游戏，使用math.random生成一个随机数（var = randomDigit），然后让用户想出一个大于1的数字。基本上，他们将数字加倍和JS将我的随机数加倍并输出。他们将数字加在一起，然后除以2并减去原来的数字，留给我（var = randomDigit）

这是我被卡住的部分。我必须这样做，如果用户不想玩，它将不会继续......我只能使用一个“if”语句。我选择使用一个prompt（）方法......如果你键入YES就行了，就像对话框说的那样，如果你按下取消它就行不通（好消息）。但如果我输入“NO”就像我不想玩游戏一样，它仍然有效。

我想要它所以程序只能在提示对话框中输入“YES”。

这是我的JS小提琴：http://jsfiddle.net/JrYAq/

 function dialog(){
var x;

var randomDigit = Math.floor((Math.random()*20)+1);

var doubleDigit = +randomDigit * 2;

var play = prompt("Would you like to play a game? If not, press cancel below.\n\nThink of a number greater than 1. Confirm you thought of a number by typing the word: YES","Type Here");

if (play==='false')
    {
    document.getElementById("pick").innerHTML="Sorry, maybe next time.";
    }       

else (play= "YES");
{
    x="1. Now double the number you thought of. I'm going to think of a number too:" + ' ' + doubleDigit +  '<br><br>' + "2. Now add my number and your doubled number together." + '<br><br>' + "Now divide the added numbers by 2, then subtract your original number. Did you get" + ' ' + randomDigit + "?" + '<br><br>' + "Pretty cool, right?"  ;
    document.getElementById("pick").innerHTML=x;
}
}

Answer 1

prompt（）函数返回用户在文本框中输入的值，而不是用户单击的按钮的值。因此，除非用户在文本框中输入“false”，否则play的值永远不会为“false”。

请改为尝试：

var play = prompt("Would you like to play a game? If not, press cancel below.\n\nThink of a number greater than 1. Confirm you thought of a number by typing the word: YES","Type Here");

if (play === "YES")
{
    x="1. Now double the number you thought of. I'm going to think of a number too:" + ' ' + doubleDigit +  '<br><br>' + "2. Now add my number and your doubled number together." + '<br><br>' + "Now divide the added numbers by 2, then subtract your original number. Did you get" + ' ' + randomDigit + "?" + '<br><br>' + "Pretty cool, right?"  ;
    document.getElementById("pick").innerHTML=x;

}       
else 
{
    document.getElementById("pick").innerHTML="Sorry, maybe next time.";
}

此外，由于这更像是或否类型的情况，您可能希望使用confirm（）而不是prompt（）。

Answer 2

小调整会做

if (play== "YES")
{
    x="1. Now double the number you thought of. I'm going to think of a number too:" + ' ' + doubleDigit +  '<br><br>' + "2. Now add my number and your doubled number together." + '<br><br>' + "Now divide the added numbers by 2, then subtract your original number. Did you get" + ' ' + randomDigit + "?" + '<br><br>' + "Pretty cool, right?"  ;
    document.getElementById("pick").innerHTML=x;
} else {
    document.getElementById("pick").innerHTML="Sorry, maybe next time.";
}

演示：Fiddle

Answer 3

else (play= "YES");

是括号中的赋值（不是比较），后跟行分隔符。它之后的块将始终执行。您的脚本目前的工作方式与编写时相同

if (play==='false') {
    document.getElementById("pick").innerHTML="Sorry, maybe next time.";
} else {
    play= "YES";
x="1. Now double the number you thought of. I'm going to think of a number too:" + ' ' + doubleDigit +  '<br><br>' + "2. Now add my number and your doubled number together." + '<br><br>' + "Now divide the added numbers by 2, then subtract your original number. Did you get" + ' ' + randomDigit + "?" + '<br><br>' + "Pretty cool, right?"  ;
document.getElementById("pick").innerHTML=x;

您似乎想要一个else-if-statement：

if (play == "false") {
    document.getElementById("pick").innerHTML = "Sorry, maybe next time.";
} else if (play == "YES") {
    x="1. Now double the number you thought of. I'm going to think of a number too:" + ' ' + doubleDigit +  '<br><br>' + "2. Now add my number and your doubled number together." + '<br><br>' + "Now divide the added numbers by 2, then subtract your original number. Did you get" + ' ' + randomDigit + "?" + '<br><br>' + "Pretty cool, right?"  ;
    document.getElementById("pick").innerHTML = x;
} /* else {
    alert("neither 'false' nor 'YES' were entered");
} */

Javascript prompt（）方法if语句

3 个答案: