- 1 year ago
node.js: take input from file using readline and process I/O in windows command prompt
To take input from a file using the readline
module in Node.js and process it in the Windows command prompt, you can follow these steps:
Set up your Node.js Environment: Ensure that you have Node.js installed on your system. You can download and install Node.js from the official Node.js website (https://nodejs.org).
Create a Node.js Script: Create a new JavaScript file with a
.js
extension, such asscript.js
, and open it in a text editor.Import the
readline
Module: In your script, import thereadline
module by requiring it at the top of your file:javascriptconst readline = require('readline');
Create a Readline Interface: Use the
readline.createInterface
method to create a readline interface that reads from the standard input (process.stdin
) and writes to the standard output (process.stdout
):javascriptconst rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});
Read Input from File: Before starting the readline interface, you need to redirect the input from a file to
process.stdin
. In the Windows command prompt, you can use the<
operator to redirect the contents of a file as input to your Node.js script:cssnode script.js < input.txt
Replace
script.js
with the actual name of your Node.js script, andinput.txt
with the path to the input file containing the data you want to process.Process the Input: Use the
rl.on('line', callback)
event to process each line of input as it is read from the file. Provide a callback function that will be executed for each line of input:javascriptrl.on('line', (line) => {
// Process the line of input
console.log(`Received line: ${line}`);
});
Replace the
console.log
statement with your own logic to process each line of input.Close the Readline Interface: After processing all the lines of input, close the readline interface using the
rl.close()
method:javascriptrl.on('close', () => {
console.log('Input processing complete');
});
Run the Script: Save your script file, open a Windows command prompt, navigate to the directory containing your script, and run the Node.js script:
cssnode script.js < input.txt
Replace
script.js
with the actual name of your Node.js script, andinput.txt
with the path to the input file.
This will read the contents of the input file line by line and process them according to your logic in the callback function.
Note: This approach assumes that your input file contains one line of input per line in the file. If your input file has a different format or structure, you may need to adjust the logic accordingly.