如何检测 args 是否为空 (discord.js)

Question

I'm doing the 8ball command for my bot (-8ball ) but when user types only 8ball command the bot crash, my code is this:

 client.on('message', message => { var command = "-8ball"; if (message.content.startsWith(command)) { const args = message.content.slice(command.length).split(/ +/g); let respuesta = ["Si", "No", "Tal vez", "Obvio", "Yo digo que si", "Yo digo que no", "Probablemente"] var random = respuesta[Math.floor(Math.random() * respuesta.length)] const embed = new Discord.MessageEmbed() .addField("Pregunta:", `${args.join(" ")}`) .addField("Respuesta:", `${random}`) .setColor("RANDOM") message.channel.send(embed) } });

how i can detect if the args are empty?

Answer 1

Since 0 is falsy:

 console.log(0 == false);

You could use Array.prototype.length (which will return 0 if there are no elements in the array)

client.on("message", (message) => {
  var command = "-8ball";
  if (message.content.startsWith(command)) {
    const args = message.content.slice(command.length).split(/ +/g);
    if (!args.length)
      return message.channel.send('You did not input a question');
    let respuesta = [
      "Si",
      "No",
      "Tal vez",
      "Obvio",
      "Yo digo que si",
      "Yo digo que no",
      "Probablemente",
    ];
    var random = respuesta[Math.floor(Math.random() * respuesta.length)];
    const embed = new Discord.MessageEmbed()
      .addField("Pregunta:", `${args.join(" ")}`)
      .addField("Respuesta:", `${random}`)
      .setColor("RANDOM");
    message.channel.send(embed);
  }
});

Answer 2

this is true only if args is an array and is not empty

if (args instanceof Array && args.length)

use this if you need it the other way around

if (!(args instanceof Array && args.length))

Answer 3

You can check for an empty array by simply checking its length property.

For example !args.length will return true if args has no elements, false if it has atleast 1 or more elements inside it

You can use this to check if args is empty

if (!args.length) {
   // Code To Execute If Args Is Empty
}

More About Arrays

Answer 4

您可以只测试数组的第一个元素。

if(!args[0]) return;