how to execute Javascript in shell

Question

JS:

#!/usr/bin/env node
const util = require("util"),
    inquirer = require("inquirer")
function promptUser() {
    inquirer.prompt([
        {
            type: "list",
            name: "scheme",
            message: "How would you like to build",
            choices: [
                {
                    name: "build develop",
                    value: "develop"
                }, {
                    name: "build product",
                    value: "product"
                }
            ]
        }
    ], earlyAnswers => {
        console.log(earlyAnswers.scheme);
    });
}
promptUser();

it will ask a question and I can select a answer, log answer, like:

I want to exec this js in shell:

#!/bin/sh
echo 123
a=`node ./test2.js`

let a = answer, but can't exec like:

how do I exec this JS?

Joe · Accepted Answer · 2017-02-06 09:56:15Z

Your javascript is actually running, but your backticks in the command

a=`node ./test2.js`

cause the shell to capture standard out and assign it to the variable a. All of stdout is captured, not just the last line, so nothing is presented to the user.

One possible way to solve this is to use the node.js process's exit code. Here is a generic script that will accept the prompt an options on the command line, and set its exit code to the zero-based index of the selection.

#! /usr/bin/env node --harmony_destructuring
util = require("util");
inquirer = require("inquirer");

var [program, file, textprompt, ...args] = process.argv

var choices = [];
args.forEach(function(E) {
    var [name, value] = E.split(":",2);
    choices.push({name: name, value: value});
});

function promptUser() {
    inquirer.prompt([
        {
            type: "list",
            name: "scheme",
            message: textprompt,
            choices: choices
        }
    ]).then(function(answer) {
        if (answer && answer.scheme) {
            position = choices.findIndex(function(E) { return E.value == answer.scheme; });
            process.exit(position);
        } else {
            process.exit(-1);
        }
    })
}
if (choices.length > 0)
    promptUser();

Which could be used like this:

#! /bin/bash
./test2.js "How would you like to build?" "build develop:develop" "build product:product"
selected=$?
case $selected in
    0) echo "Selected develop";; 
    1) echo "Selected product";;
    *) echo "Invalid selection";;
esac

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