NoMoreAcronyms/commands/countChars.ts

const { SlashCommandBuilder, Discord, codeBlock } = require('discord.js');

module.exports = {
	data: new SlashCommandBuilder()
		.setName('count_chars')
		.setDescription('Counts the number of characters in a string')
		.addStringOption( option =>
			option.setName('string')
			.setDescription("String to count characters in")
			.setRequired(false)
			)
			.addStringOption( option =>
				option.setName('messageid')
				.setDescription("Message ID of message to count characters in")
				.setRequired(false)
				),
	async execute(interaction) {
		var inputString;
		
		if (interaction.options.getString('string') !== null) {
			inputString = interaction.options.getString('string');
		} else if (interaction.options.getString('messageid') !== null) {
			var messageId = interaction.options.getString('messageid');
			const messagefromId = await client.channels.cache.get(interaction.channel.id).messages.fetch(messageId);
			inputString = messagefromId.content;
		}
		
		await interaction.reply("Input: `" + inputString + "`\n" + "Output: " + codeBlock("", countChars(inputString)));
        console.log("User " + interaction.user.tag + " ran /count_chars");
	},
};

function countChars(string) {
	var outputString = "";
	string = string.toLowerCase();
	var letterCount = Array(26).fill(0); // Creates an array with 26 values, all equaling 0.
	for (let i = 0; i < string.length; ++i) {
		let currentChar = string.charAt(i);
		let arrayIndex = currentChar.charCodeAt(0) - 97;
		if (string.charAt(i).search(/^[a-z]+$/) === 0)  {
			letterCount[arrayIndex]++;
		}
	}
	for (let i = 0; i < letterCount.length; ++i) {
		if (letterCount[i] > 0) {
				outputString += "Number of " + String.fromCharCode(i + 97).toUpperCase() + "'s: " + letterCount[i] + "\n"; 
		}
	}
	return outputString;
}
//console.log(countChars("test string"));