How to use the start function from commander
Find comprehensive JavaScript commander.start code examples handpicked from public code repositorys.
commander.start is a function in the Commander.js library that starts the parsing of command-line arguments and executes the associated commands.
GitHub: scality/cloudserver
![scality profile picture](/scality.png?size=40)
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// `commander.metric` should be defined. const metric = metricType === 'buckets' ? 'buckets' : commander.metric; requiredOptions[metric] = commander[metric]; // If not recent listing, the start option must be provided if (!recent) { requiredOptions.start = commander.start; } Object.keys(requiredOptions).forEach(option => { if (!requiredOptions[option]) { logger.error(`missing required option: ${option}`);
GitHub: savemeour/1234
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if (!opts.args[0]) { throw new Error('Please supply a grammer.js file path as a command-line argument'); } var filename = require('path').resolve(opts.args[0]); var grammar = nearley.Grammar.fromCompiled(require(filename)); if (opts.start) grammar.start = opts.start var parser = new nearley.Parser(grammar, { keepHistory: true, });
+ 3 other calls in file
How does commander.start work?
commander.start
is a function in the Commander.js library that starts the parsing of command-line arguments and executes the associated commands.
When called, commander.start
first parses the command-line arguments using the configuration set up by the commander
instance. This includes parsing the arguments for options, commands, and their arguments, and storing the results in a JavaScript object.
After the arguments are parsed, commander.start
determines which command was specified based on the parsed arguments, and executes the associated callback function. If no command was specified, commander
will execute the default
command if one was defined, or print the help text for the program.
The commander.start
function can be useful for creating command-line tools that can be run from a terminal or command prompt, such as utility scripts or command-line interfaces for applications.
For example, suppose we have a simple command-line tool that accepts a single command greet
with an optional argument name
, which prints a greeting message to the console:
javascriptconst { Command } = require('commander');
const program = new Command();
program
.command('greet [name]')
.description('Print a greeting message')
.action((name = 'World') => {
console.log(`Hello, ${name}!`);
});
program.parse(process.argv);
In this example, we use commander
to define a greet
command with an optional name
argument. When the command is executed, commander
will call the action
function, passing in the value of the name
argument if one was provided, or the default value 'World'
. We use console.log
to print the greeting message to the console.
We then call program.parse(process.argv)
to start the parsing of the command-line arguments and execute the greet
command if it was specified. If no command was specified, commander
will print the help text for the program.
When run from the command line with node greet.js greet John
, this script would output the greeting message Hello, John!
.
Ai Example
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const { Command } = require("commander"); const fs = require("fs"); const program = new Command(); program .version("1.0.0") .description("Read a file and print its contents to the console") .argument(" ", "The file to read") .action((file) => { fs.readFile(file, "utf-8", (err, data) => { if (err) { console.error(err.message); } else { console.log(data); } }); }); program.parse(process.argv);
In this example, we use commander to define a command-line tool that accepts a single argument , representing the file to read. When the command is executed, commander will call the action function, passing in the value of the argument. We then use the fs module to read the contents of the specified file, and print them to the console using console.log. If an error occurs while reading the file, we print the error message to the console using console.error. We then call program.parse(process.argv) to start the parsing of the command-line arguments and execute the action function if the argument was specified. When run from the command line with node readfile.js myFile.txt, this script would output the contents of the myFile.txt file to the console.
commander.Option is the most popular function in commander (1786 examples)