Javascript：期待一个标识符，而是看到“其他”。失踪 ”;”声明之前答案

【问题标题】：Javascript: Expecting an Identifier and instead saw 'else'. Missing ";" before statementJavascript：期待一个标识符，而是看到“其他”。失踪 ”;”声明之前
【发布时间】：2013-10-01 17:04:02
【问题描述】：

我正在通过代码学院自学 javascript，并不断收到“意外的令牌”。我错过了什么：

function creditCheck(income) {
    var ans = 100; if(income>=100);     
    return("You earn a lot of money! You qualify for a credit card."); 
} 
else {     
    return("Alas you do not qualify for a credit card. Capitalism is cruel like that." ); 
}

creditCheck(75);
信用检查(125);
信用检查（100）；

【问题讨论】：

var ans = 100; if(income>=100); 从本行末尾删除 ; 并添加 {
return 语句后也需要相应的 }。

标签： javascript function if-statement

【解决方案1】：

JSLint 会抱怨给出的例子。它更喜欢：

function creditCheck(income) {
   var ans = 100; 
   if (income >= 100) {
       return("You earn a lot of money! You qualify for a credit card."); 
   } 
   return("Alas you do not qualify for a credit card. Capitalism is cruel like that."); 
}

我之所以提到这一点，是因为代码示例中的 else 如果只包含最终返回，则它是不必要的。

【讨论】：

【解决方案2】：

删除一个；并添加 {

function creditCheck(income) 
{
       var ans = 100; 
       if(income>=100)
       {
           return("You earn a lot of money! You qualify for a credit card."); 
       } 
       else
       {     
           return("Alas you do not qualify for a credit card. Capitalism is cruel like that."   ); 
       }
}

如果你不想放 { 你可以写..

function creditCheck(income) 
{
       var ans = 100; 
       if(income>=100)
           return("You earn a lot of money! You qualify for a credit card."); 
       else
           return("Alas you do not qualify for a credit card. Capitalism is cruel like that."   ); 
}

【讨论】：

【解决方案3】：

嗯，这就是你解决代码的方法：

function creditCheck(income) {
    var ans = 100; 
    if(income>=100){     
        return("You earn a lot of money! You qualify for a credit card."); 
    }else {     
        return("Alas you do not qualify for a credit card. Capitalism is cruel like that." ); 
    }
}

else 应该在 if 语句之后

【讨论】：

就是这样！谢谢！

【解决方案4】：

您的代码现在执行function creditcheck() { ...} else {...} 函数没有else{}。你在 if 上犯了一个小错误，这是正确的方法：

function creditCheck(income) {
    var ans = 100;
    if(income>=100){
        return("You earn a lot of money! You qualify for a credit card."); 
    } 
    else {     
        return("Alas you do not qualify for a credit card. Capitalism is cruel like that." ); 
    } 
}

或者我会使用的方法：

function creditCheck(income) {
    var ans = 100;
    var returnValue;
    if(income>=100){ returnValue = "You earn a lot of money! You qualify for a credit card."; } 
    else {           returnValue = "Alas you do not qualify for a credit card. Capitalism is cruel like that."; } 

    return returnValue; // Return it at the end. This way the action `return` only happends at the end
}

这更容易调试。如果要检查返回的是哪个值，只需在返回值上方添加 console.log(returnValue); 一行即可。

【讨论】：

【解决方案5】：

确保每个左括号都有一个匹配的右括号很重要。

您的代码：

function creditCheck(income) {
    var ans = 100;
    if(income>=100);
    return("You earn a lot of money! You qualify for a credit card."); 
    } 
    else {     
        return("Alas you do not qualify for a credit card. Capitalism is cruel like that." ); 
}

格式应为：

function creditCheck(income)
{
    var ans = 100;
    // I'm assuming that you mean to compare 'income' with 'ans'
    // Notice that I replaced ';' with an opening bracket here
    if(income>=ans) 
    {  
        return("You earn a lot of money! You qualify for a credit card."); 
    }
    else
    {     
        return("Alas you do not qualify for a credit card. Capitalism is cruel like that." );
    }
    // And here I've added a closing bracket
}

当您在由括号形成的条件块（例如if）中只有一个操作时，您实际上不需要开始和结束括号。见下文。

// 
function creditCheck(income)
{
    var ans = 100;
    // See, no more brackets here
    if(income>=ans) 
        return("You earn a lot of money! You qualify for a credit card."); 
    else
        return("Alas you do not qualify for a credit card. Capitalism is cruel like that." );
}

【讨论】：