如何在Node.js REPL上使用`prompt`

Question

I am using node as a JavaScript REPL. Is it possible to use prompt as in the example below?

function foo() {
    var i = prompt("enter value for i: ");
    console.log('i is now: '+i);
}

foo();

When I run the above code (loading it from file j.js ), I get:

$ node
> .load j.js
>     function foo() {
...         var i = prompt("enter value for i: ");
...         console.log('i is now: '+i);
...     }
undefined
>     
undefined
>     foo();
ReferenceError: prompt is not defined
    at foo (repl:2:9)
    at repl:1:1
    at REPLServer.self.eval (repl.js:110:21)
    at repl.js:249:20
    at REPLServer.self.eval (repl.js:122:7)
    at Interface.<anonymous> (repl.js:239:12)
    at Interface.emit (events.js:95:17)
    at Interface._onLine (readline.js:203:10)
    at Interface._line (readline.js:532:8)
    at Interface._ttyWrite (readline.js:815:20)

... failing a solution to the above problem, is that some other tool (console-based, not browser-based) I can use as a JavaScript REPL?

Answer 1

So you can read stdio from the script you're running, which is the main way to do it from the console. There's a number of modules for making things interactive, but the straight node core way to do it is with readline:

var readline = require('readline');

var rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

rl.question("What do you think of node.js? ", function(answer) {
  // TODO: Log the answer in a database
  console.log("Thank you for your valuable feedback:", answer);

  rl.close();
});

Answer 2

Prompt is a statement and you're using it as an object. Instead of doing this:

    var i = prompt("enter value for i: ");

You should do this:

     prompt("enter value for i: ");