Question

我正在使用代码学院网站学习JavaScript，每当我尝试if / else计划时，它总会出现expected a identifier。我不知道我做错了什么。我的程序看起来像这样：

 confirm("Are you ready?")
    var age = prompt("What's your age?")
    if (age <= 18)
    console.log{"You are allowed to play but I take no responsibily";
    }
    else 
    {
    console.log ;"Have fun playing"
    }

Answer 1

要调用console.log函数，您需要围绕其参数（圆形）括号。你也错过了if条件后的左大括号：

confirm("Are you ready?")
var age = prompt("What's your age?");
if (age <= 18) {
    console.log( "You are allowed to play but I take no responsibily" );
} else {
    console.log( "Have fun playing" );
}

顺便说一下，如果if，else，for等正文中只有一个语句，则可省略大括号。但是，使用适当的缩进很重要然后：

confirm("Are you ready?")
var age = prompt("What's your age?")
if (age <= 18)
    console.log( "You are allowed to play but I take no responsibily" );
else
    console.log( "Have fun playing" );

另请注意prompt()正在返回一个字符串，在将其与18进行比较之前，您可能希望parse into a number：

 var age = parseInt( prompt("What's your age?"), 10);

Answer 2

if(confirm("Are you ready?"))
{
    var age = prompt("What's your age?");
    if (age <= 18)
    {
        console.log("You are allowed to play but I take no responsibily");
    }
    else 
    {
        console.log("Have fun playing");
    }
}

您需要使用正确的语法。例如，console.log是console.log("text")

Answer 3

确保每个陈述后都有一个分号

confirm("Are you ready?")
var age = prompt("What's your age?")

需要阅读

confirm("Are you ready?");
var age = prompt("What's your age?");

如何修复预期的标识符

3 个答案: