Usage Structure

<> required argument, [] optional argument <Name:Type{Min,Max}/Regex/Flags>

• Name Mostly used for debugging message, unless the type is Literal in which it compares the argument to the name.
• Type The type of variable you are expecting.
• Min, Max Minimum or Maximum for a giving variable (works on strings in terms of length, and on all types of numbers in terms of value) You are allowed to define any combination of min and max. Omit for none, {min} for min, {,max} for max. If you set min and max with the same integer, then the provided string must have equal length.
• Regex, Flags A regular expression with double escaped \ to match against the argument. It is only valid for regex types of arguments, but gives you great flexibility on custom argument parsing. Flags are regex flags to apply to the regex pattern.
• Special Repeat Tag [...] will repeat the last usage optionally until you run out of arguments. Useful for doing something like <SearchTerm:str> [...] which will allow you to take as many search terms as you want, per your Usage Delimiter.

Note: You can set multiple options in an argument by writting |. For example: <Message:msg|Content:string{4,16}> will work when you provide a message ID or a string with a length between 4 and 16 (including both limits).

Usage Types

Note: Literal is very useful in arguments with multiple options.

Using arguments in your command.

Now, after we understand how to configurate the command, we'll start writting it:

async run(msg, [...params]) {
    // This is where you place the code you want to run when your command is called
}

[...params] represents a variable number of parameters given when the command is run. The name of the parameters in the array (and their count) is determined by the usage property and its given arguments.

Note that the commands' parameters are an array. This is a trick called Destructuring assignment.

For example, when you have: "<Message:msg> <delete|edit> [newContent:string]" as your usage, and "|" as your usageDelim, then the following code block is an example of how it would look like, and how we would work with them.

async run(msg, [message, action, newContent]) {
  // code
};

In which message is the argument assigned to the message object as provided in <Message:msg> argument from usage. Same does action for <delete|edit> and respectively.

Keep in mind that we declared newContent as an optional argument, if it's not provided, it'll return undefined.

Keep in mind that arguments are delimited by the character or combination of characters written in usageDelim. In this case, we have assigned the character | for it. How do we use this command? Easy:

+messager 293107496191655936|delete

The line above will execute the command with the name messager (or a command with messager as an alias), it'll use Channel.messages.fetch. If the message is not found (you mistyped it or the message is in another channel) it'll warn you that the message hasn't been found. The next argument is a literal, in which must be either delete or edit.

Using regex arguments in your command.

Regex arguments give you even more flexibility to define custom matching. Regex in usage needs to be double escaped like the following: <hexColor:regex/#?([\\da-f]{6})/i>. That regex will resolve into: /#?([\da-f]{6})/i which should match any hexcolor string. When you use a regex argument, the result of RegExp.prototype.exec will be passed into the command.

So we can do the following destructuring to get the first matching group of the hexColor arg:

async run(msg, [[, hexColor]]) {
  // code
};

So the command +getrgb #ab24ff would make hexColor: 'ab24ff'.