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Read a Text Stream Line by Line with lazylines for Node.js

· Web Dev Zone

The new Node.js module “lazylines” allows you to read a text stream, one line at a time, lazily.

 

Examples

The following code reads input from stdin and prepends a number to each line.

    var ll = require("lazylines.js");

    process.stdin.resume();
    var inp = new ll.LineReadStream(process.stdin);
    var count = 1;
    inp.on("line", function (line) {
        console.log(count+": "+ll.chomp(line));
        count++;
    });

There are more examples in the demo/ directory. lazylines is very handy for shell programming. For example, you can implement a script that lets you do the following. 

    # List jpg files, oldest first (-t -r), then wrap
    ls -1 -t -r *.jpg | addlinecounts.js 'mv "{line}" {padi}.jpg' | bash

The above executes commands such as 

    mv "new.jpg" 001.jpg
    mv "newer.jpg" 002.jpg
    mv "newest.jpg" 003.jpg

Installation

    npm install lazylines

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Published at DZone with permission of Axel Rauschmayer , DZone MVB .

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