如何摆脱 Discord 嵌入中的 "undefined"

Question

我正在努力使这个 Discord 嵌入的输出对于嵌入的 Bot, Mute, and Deafen 部分不会是 "undefined"。

我试图将一些 var 更改为 "let" 或 "const" 我篡改了 aboutuser 部分以将其更改为不同的内容。我弄乱了代码的 if 部分。

这是代码。

async run(message, args){
    if (message.channel instanceof discord.DMChannel) return message.channel.send('This command cannot be executed here.')
    else
    var serv = message.guild

    if (serv.explicitContentFilter == 0) {
        var eFC = "Don't Scan Any messages";
    }
    if (serv.explicitContentFilter == 1) {
        var eFC = "Scan for users without a role.";
    }
    if (serv.explicitContentFilter == 2) {
        var eFC = "Scan every message";
    }
///////////////////////////////////////////////////////////////////////////////////////////////////
    if (serv.verificationLevel == 4) {
        var verL = "Intense (Verified Account & Verified Phone linked)";
    } 

    if (serv.verificationLevel == 3) {
        var verL = "Secure (Verified Account & Guild member for 10+ minutes)";
    } 
    if (serv.verificationLevel == 2) {
        var verL = "Medium (Verified Account for 5 minutes+)";
    }    
    if (serv.verificationLevel == 1) {
        var verL = "Low (Verified Account)";
    } 
    if (serv.verificationLevel == 0) {
        var verL = "None (No Restriction)";
    }  
//////////////

if (serv.region == `brazil`) {
    var regio = "Brazil";
}  

if (serv.region == `eu-central`) {
    var regio = "Central Europe";
}  

if (serv.region == `hongkong`) {
    var regio = "Hong Kong";
}  

if (serv.region == `japan`) {
    var regio = "Japan";
}  

if (serv.region == `russia`) {
    var regio = "Russia";
}  

if (serv.region == `singapore`) {
    var regio = "Singapore";
}  

if (serv.region == `southafrica`) {
    var regio = "South Africa";
}  

if (serv.region == `sydney`) {
    var regio = "Sydney";
} 

if (serv.region == `us-central`) {
    var regio = "Central US";
}  

if (serv.region == `us-east`) {
    var regio = "East US";
}  

if (serv.region == `us-south`) {
    var regio = "South US";
}  

if (serv.region == `us-west`) {
    var regio = "West US";
}  

if (serv.region == `eu-west`) {
    var regio = "West Europe";
}  
//
if (serv.defaultMessageNotifications == `ALL`) {
    var defn = "Send all Messages";
}  

if (serv.defaultMessageNotifications == `MENTIONS`) {
    var defn = "Only @everyone";
} 

    var myInfo = new discord.RichEmbed()
        .setAuthor(`${serv.name}'s guild info`,`${message.guild.iconURL}`)
        .addField(`AFK Channel`,`${serv.afkChannel}`,true)
        .addField(`AFK Timeout`,`${serv.afkTimeout}s`,true)
        .addField(`Channels`,`${serv.channels.size}`,true)
        .addField(`Creation of Guild`,`${serv.createdAt}`,true)
        .addField(`Default Notification`, defn,true)
        .addField(`Explicit Content Filter Level`, eFC,true)
        .addField(`Guild ID`,`${serv.id}`,true)
        .addField(`How much members`,`${serv.memberCount}`,true)
        .addField(`Owner`,`${serv.owner}`,true)
        .addField(`Region`, regio,true)
        .addField('Roles', `Please do s!roles to find server roles!`, true)
        /* serv.roles.map(r => `${r}`).join(' | ') */
        .addField(`Verification Level`, verL,true)
        .setColor(0x511fdd)
        .setFooter('Aboutserver command')
        .setThumbnail(`${message.guild.iconURL}`)
        message.channel.sendEmbed(myInfo);

}

}

预期结果：机器人会说是或否，而不是未定义、真或假。实际结果：机器人的输出只是未定义。

Answer 1

这里发生了一些事情，但让我们关注主要问题；你是如何声明你的变量的。

简单来说，变量只能在声明的范围内访问（范围是{}之间的所有代码）。

我将根据你的代码用一个简短的例子来解释它。在 if 语句中声明变量，这意味着它们可以在 if 语句的范围内使用。您稍后想要在 if 语句之外和嵌入中使用这些相同的变量。因为那些变量不存在于那个范围内，所以它们是未定义的。

...
// At this point there is no variable 'eFC' available.

if (serv.explicitContentFilter == 0) {
    // Here you create the variable 'eFC' but it can only be used inside this scope, meaning it cannot be accessed outside the 'if' statement.
    var eFC = "Don't Scan Any messages";
}
if (serv.explicitContentFilter == 1) {
    // Here you create another variable with the same name, but it would end up being a different variable.
    var eFC = "Scan for users without a role.";
}

// Here there is still no variable 'eFC' available to us.
...

简单的解决方案是：在另一个范围内声明您的变量，然后再赋值。下面你可以看到一个例子：

...
// Here we create a new variable called 'eFC' which can be used within this scope
var eFC;

if (serv.explicitContentFilter == 0) {
    // Here we assign a value to the previously defined variable
    eFC = "Don't Scan Any messages";
}
if (serv.explicitContentFilter == 1) {
    // Here we assign a value to the previously defined variable
    eFC = "Scan for users without a role.";
}

// Here we can use the variable 'eFC' which will have a value
console.log(eFC);
...

如果你对你使用的所有变量都这样做，代码应该可以正常工作。

最后我想给你一些额外的帮助。我看到您已经创建了很多很多 if 语句来检查例如服务器区域或服务器验证级别。 Javascript（在许多其他编程语言中）有一个叫做 switch case 的想法，它基本上与所有这些 if 语句做同样的事情，但以更简洁的方式。查看 link，我认为它会帮助您使代码看起来更具可读性

如何摆脱 Discord 嵌入中的 "undefined"

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