creply

create read–eval–print-loop (repl) programs want to create a repl? with creply you create easily you can use it with TypeScript too!

• also see the documetation generated by typedoc

creating the repl

const creply = require("creply");
const repl = new creply({
  name: "app",
  description: "simple node.js repl app",
  version: "v1.0.0",
  history: "app.history",
  prompt: "app> ",
  prefix: "!"
});

• this will create a repl with the following options:

{
  "name": "app",
  "description": "simple node.js repl app",
  "version": "v1.0.0",
  "history": "app.history",
  "prompt": "app> ",
  "prefix": "!"
}

starting the repl

repl.start();

• this will start the repl and output the following:

app>

adding commands

• commands are added with the repl.addCommand() method
• commands are saved in the repl.commands object

repl.addCommand("hello",{ 
  description: "hello world", 
  exec: (args) => { 
   console.log("hello world")
  },
  usage: () => "hello [name]"
  })

• this will add a command with the following options:

{
  "description": "say hello",
  "exec": "[Function: exec]",
  "usage": "[Function: usage]"
}

removing commands

• commands are removed with the repl.removeCommand() method

repl.removeCommand("hello");

• this will remove the command with the name hello
• the command will be removed from the repl.commands object

updating options

• options are updated with the repl.set() method
• options are saved in the repl.options object
• example updating the prompt

repl.set({
  prompt: "cli> "
});

• this will update the prompt to cli>
• output will be:

cli>

getting options

• options are retrieved with the repl.get() method

console.log(repl.get("prompt"));

• this will output the prompt
• output will be:

cli>

listening to events

• events are listen with the repl.on() method

• when you listen an event the repl will not prints the data except the event uncaught-error

• example listening to the line event

• the event will be called when the user types a line

repl.on("line", (line) => {
  console.log("line: " + line);
});

• example listening to the uncaught-error event
• the event will be called when the repl throws an error

repl.on("uncaught-error", (err) => {
  console.log("uncaught-error: " + err);
});

• example listening the keypress event
• the event will be called when the user press a key

repl.on("keypress", (char, key) => {
  console.log("keypress: " + key);
});

• example listening to the exit event
• this event will be called when the repl is closed

repl.on("exit", () => {
  console.log("exit");
});

• example listening to the cursor-move event
• this event will be called when the cursor moves

repl.on("cursor-move", (cursor) => {
  console.log("cursor-move: " + cursor);
});

• example listening to the command event
• this event will be called when the repl executes a command

repl.on("command", (command, args) => {
  console.log("command: " + command);
});

• example listening to the command-not-found event
• this event will be called when the repl executes a command that doesn't exist

repl.on("command-not-found", (command) => {
  console.log("command-not-found: " + command);
});

• example listening to the did-you-mean event
• this event will be called when repl try to mean the command

repl.on("did-you-mean", (command, didYouMean) => {
  console.log("did-you-mean: " + didYouMean);
});

• example listening to the command-not-specified event
• this event will be called when the repl executes a command that doesn't have a name

repl.on("command-not-specified", () => {
  console.log("command-not-specified");
});

• example listening to the start event
• this event is triggered when the repl starts
• the listener must be before the repl.start() call

repl.on("start", () => {
  console.log("started!");
});

readline and rl

• the readline is the readline library used by the creply
• the rl is the readline interface used by the creply
• to get readline use repl.readline
• to get rl use repl.rl but you need to start the repl first by using repl.start()

view command usage

• the repl.usage() method will print the usage of the command

repl.usage("hello"); // hello [name]

• you can type help [command] to see the usage of the command on the repl

app> help hello

• output:

hello [name]

common problems

• if console.log prints out of the repl, you can use the repl.log() method
• the repl.log() method will print out the data to the repl
• this methods clear prompt and move the cursor to the start of the line

repl.log("hello");

• output:

cli>
hello
cli>