TypeError：无法读取未定义的属性“数据”| discord.js

Question

So I am making a Discord bot and I have a meme command that gets memes from r/memes, however sometimes it gives a meme and sometimes the code crashes and gives this error in console:

TypeError: Cannot read property 'data' of undefined

I'm not too sure what it could be so if anyone could help me out that would help a lot.

Here's my !meme command code:

const https = require('https');
const Discord = require('discord.js');
const url = 'https://www.reddit.com/r/memes/hot/.json'

module.exports = {
    name: 'meme',
    description: 'sends meme',
    execute(message, args) {

        https.get(url, (result) => {
            var body = ''
            result.on('data', (chunk) => {
                body += chunk
            })

            result.on('end', () => {
                var response = JSON.parse(body)
                var index = response.data.children[Math.floor(Math.random() * 99) + 1].data

                if (index.post_hint !== 'image') {

                    var text = index.selftext
                    const textembed = new Discord.MessageEmbed()
                        .setTitle(subRedditName)
                        .setColor(4388341)
                        .setDescription(`[${title}](${link})\n\n${text}`)
                        .setURL(`https://reddit.com/${subRedditName}`)

                    message.channel.send(textembed)
                }

                var image = index.preview.images[0].source.url.replace('&', '&')
                var title = index.title
                var link = 'https://reddit.com' + index.permalink
                var subRedditName = index.subreddit_name_prefixed

                if (index.post_hint !== 'image') {
                    const textembed = new Discord.MessageEmbed()
                        .setTitle(subRedditName)
                        .setColor(4388341)
                        .setDescription(`[${title}](${link})\n\n${text}`)
                        .setURL(`https://reddit.com/${subRedditName}`)

                    message.channel.send(textembed)
                }
                console.log(image);
                const imageembed = new Discord.MessageEmbed()
                    .setTitle(subRedditName)
                    .setImage(image)
                    .setColor(4388341)
                    .setDescription(`[${title}](${link})`)
                    .setURL(`https://reddit.com/${subRedditName}`)
                message.channel.send(imageembed)
            }).on('error', function (e) {
                console.log('Got an error: ', e)
            })
        })
    },
}

Answer 1

It's because you're setting a hardcoded number ( 99 ) to get a random element from the response.data.children array. I've just checked the length of that array and it was 26. If your random number will be larger than that (and there is as you're generating a random number between 1 and 100), response.data.children[randomNumber] will be undefined .

Try to use the array's length as the max number instead so it will never be more than the number of elements:

let index =
  response.data.children[
    Math.floor(Math.random() * response.data.children.length)
  ].data;

The full code:

module.exports = {
  name: 'meme',
  description: 'sends meme',
  execute(message, args) {
    https.get(url, (result) => {
      let body = '';

      result.on('data', (chunk) => {
        body += chunk;
      });

      result
        .on('end', () => {
          const response = JSON.parse(body);
          const index =
            response.data.children[
              Math.floor(Math.random() * response.data.children.length)
            ].data;

          const image = index.preview.images[0].source.url.replace(
            '&',
            '&',
          );
          const title = index.title;
          const link = 'https://reddit.com' + index.permalink;
          const subRedditName = index.subreddit_name_prefixed;

          if (index.post_hint !== 'image') {
            const text = index.selftext;
            const textembed = new Discord.MessageEmbed()
              .setTitle(subRedditName)
              .setColor(4388341)
              .setDescription(`[${title}](${link})\n\n${text}`)
              .setURL(`https://reddit.com/${subRedditName}`);

            message.channel.send(textembed);
          }

          const imageembed = new Discord.MessageEmbed()
            .setTitle(subRedditName)
            .setImage(image)
            .setColor(4388341)
            .setDescription(`[${title}](${link})`)
            .setURL(`https://reddit.com/${subRedditName}`);

          message.channel.send(imageembed);
        })
        .on('error', function (e) {
          console.log('Got an error: ', e);
        });
    });
  },
};