How to use the command function from yargs

yargs.command is a method in the yargs library that allows you to define a new command-line command with its own options and functionality.

How does yargs.command work?

In the yargs library, yargs.command is a method that allows you to define a new command-line command with its own options and functionality. This is useful for creating complex command-line interfaces with multiple commands, each of which may have its own arguments and behaviors. When you call yargs.command, you pass in an object that describes the command, including its name, aliases, description, options, and handler function. The options can include both positional arguments and flags with values, and can have various types, such as boolean, string, or number. The handler function is called when the command is executed, and receives the parsed command-line arguments as its first parameter. For example, here's how you might define a new command using yargs.command: javascript Copy code {{{{{{{ const yargs = require('yargs'); yargs.command({ command: 'greet ', aliases: ['hello', 'hi'], describe: 'Greet someone by name', builder: { title: { describe: 'Title to use when greeting', type: 'string', default: 'Mr.' } }, handler: (argv) => { console.log(`Hello, ${argv.title} ${argv.name}!`); } }); In this example, we're using yargs.command to define a new command called greet, which takes a required positional argument . We also define two aliases for the command, hello and hi, using the aliases option. We specify a description for the command using the describe option, and define an optional flag called title using the builder option. The title flag has a default value of 'Mr.' and is of type string. Finally, we define the handler function for the command using the handler option. The handler function is called when the greet command is executed, and receives an object with the parsed command-line arguments as its first parameter. In this case, we simply log a greeting to the console that includes the value of the title and name arguments. Overall, yargs.command is a powerful method in yargs that allows you to define complex command-line interfaces with multiple commands and options, making it easier to build robust command-line tools and utilities.

Ai Example

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const yargs = require("yargs");

yargs.command({
  command: "greet ",
  aliases: ["hello", "hi"],
  describe: "Greet someone by name",
  builder: {
    title: {
      describe: "Title to use when greeting",
      type: "string",
      default: "Mr.",
    },
  },
  handler: (argv) => {
    console.log(`Hello, ${argv.title} ${argv.name}!`);
  },
});

// Parse the command-line arguments
const argv = yargs.parse();

// Call the appropriate command based on the parsed arguments
if (argv._[0] === "greet") {
  yargs.showHelpOnFail(false);
  yargs.exitProcess(false);
  yargs.parse(["greet", argv._[1]]);
}

In this example, we're using yargs.command to define a new command called greet, which takes a required positional argument . We also define two aliases for the command, hello and hi, using the aliases option. We specify a description for the command using the describe option, and define an optional flag called title using the builder option. The title flag has a default value of 'Mr.' and is of type string. Finally, we define the handler function for the command using the handler option. The handler function is called when the greet command is executed, and receives an object with the parsed command-line arguments as its first parameter. In this case, we simply log a greeting to the console that includes the value of the title and name arguments. We then parse the command-line arguments using yargs.parse. If the first positional argument is greet, we call yargs.parse again with an array containing the greet command and the second positional argument. This ensures that the greet command is executed with the appropriate arguments. Overall, this example demonstrates how you can use yargs.command to define a new command with its own options and functionality, and then call that command based on the parsed command-line arguments.