Is there way take dynamic input using stdin in NodeJS?

Question

I have to get 1st input of the Number of Test Cases:

if the test case is got input of 1, Then I need to get 2 more inputs.

if the test case is got input of 2, Then I need to get 4 more inputs.

Is it possible to use STDIN for dynamic input using 1st input in NodeJS?

Sure, why not? You can code it to do pretty much whatever you want. — Dave Newton
– Dave Newton, Commented Feb 23, 2022 at 18:19
Does this answer your question? Node detect child_process waiting to read from stdin — evolutionxbox
– evolutionxbox, Commented Feb 23, 2022 at 18:22

nah0131 · Accepted Answer · 2022-02-23 18:42:27Z

1

Sure, this is possible. In NodeJS, you could use the built-in readline module. Nothing prevents you from building logic so that a dynamic number of inputs are read. For example, something like this might help you:

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

rl.question("How many entries do you need to create? ").then(async answer => {
    const numberOfEntries = Number(answer);

    // Validate input
    if (!Number.isInteger(numberOfEntries) || numberOfEntries < 1)
        throw new Error("Invalid number of entries");

    // Read dynamic number of inputs
    const entries = [];
    for (let i = 0; i < numberOfEntries; i++) {
        const foo = await rl.question("Foo? ");
        const bar = await rl.question("Bar? ");
        
        entries.push({foo, bar});
        console.log(`Entry ${i} with foo = ${foo} and bar = ${bar}`);
    }
 
    rl.close();
});

answered Feb 23, 2022 at 18:42

nah0131

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3 Comments

Amitesh Kumar Over a year ago

Which version of nodejs are you using?

Amitesh Kumar Over a year ago

I am getting this error - rl.question("How many entries do you need to create? ").then(async answer => { ^ TypeError: Cannot read properties of undefined (reading 'then') at Object.<anonymous> (C:\Users\bhanu\OneDrive\Desktop\node_pro\abcd.js:8:56)

nah0131 Over a year ago

The readline module has one callback-version and one promise-version. This example is using the promise-version (obviously) so make sure to import readline/promises

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