Javascript if/else语句

Question

我的语法出错。我不知道我哪里错了。

// Check if the user is ready to play! 
confirm("I am ready to play!"); 
var age = 13; 
var age = prompt("What's your age?"); 
if(var age === 13) 
{ 
    console.log("You are allowed to play but at your own risk."); 
} 
else 
{ 
    console.log(Play on!"); 
} 

Answer 1

你只需要声明一个变量var一次：

// Check if the user is ready to play! 
confirm("I am ready to play!"); 
var age = prompt("What's your age?"); 
if (age === '13') { // age will be a string 
    console.log("You are allowed to play but at your own risk."); 
} else { 
    console.log("Play on!"); 
} 

，因为你不能声明if语句中的变量，得到一个语法错误。

此外，请注意，您在最近的console.log中缺少";这也会导致语法错误。

你也有一些逻辑问题。首先，age将是一个字符串，而不是整数，因此age === 13将永远不匹配。另外，初始化age到13没有意义，并立即重新分配它。

Answer 2

//this is another solution 
confirm("I am ready to play!"); 
var age = prompt("What's your age?");//input type will be string 
age = parseInt(age);     //can convert to number by parseInt 
if(age === 13) 
{ 
alert("You are allowed to play but at your own risk."); 
} 
else 
{ 
alert("Play on!"); 
}