javascript - 如何修复错误无法读取未定义的属性 'trim`

Question

代码:

case `prefix`:
    var prfx = args[3];
    if (!prefix) return msg.reply(`prefix ?`);
    data.prefix = prfx.trim();
    msg.channel.send(`done , my prefix now is : ${prfx}`);
break;

错误:

TypeError: Cannot read property 'trim' of undefined at Client.client.on.msg

Answer 1

在您的情况下，prfx未定义，但您正在检查变量prefix，并且仅在该变量为假时才返回。您还必须检查 prfx 或仅检查 prfx。

case `prefix`:
   var prfx = args[3];
   if (!prefix || !prfx) { // Check for prfx as well, since that one could be undefined, maybe !prefix is not even needed or just mispelled
      return msg.reply(`prefix ?`);
   }
   data.prefix = prfx.trim();
   msg.channel.send(`done , my prefix now is : ${prfx}`);
   break;