How to remove one line from a txt file

Question

I have the following text file ("test.txt") that I want to manipulate in node.js:

world food 

I want to remove the first line so that food becomes the first line instead. How can I do that?

Answer 1

var fs = require('fs') fs.readFile(filename, 'utf8', function(err, data) {     if (err)     {         // check and handle err     }     // data is the file contents as a single unified string     // .split('\n') splits it at each new-line character and all splits are aggregated into an array (i.e. turns it into an array of lines)     // .slice(1) returns a view into that array starting at the second entry from the front (i.e. the first element, but slice is zero-indexed so the "first" is really the "second")     // .join() takes that array and re-concatenates it into a string     var linesExceptFirst = data.split('\n').slice(1).join('\n');     fs.writeFile(filename, linesExceptFirst, function(err, data) { if (err) {/** check and handle err */} }); }); 

Answer 2

I just came across the need to be able to exclude several lines in a file. Here's how I did it with a simple node function.

const fs = require('fs');  const removeLines = (data, lines = []) => {     return data         .split('\n')         .filter((val, idx) => lines.indexOf(idx) === -1)         .join('\n'); }  fs.readFile(fileName, 'utf8', (err, data) => {     if (err) throw err;      // remove the first line and the 5th and 6th lines in the file     fs.writeFile(fileName, removeLines(data, [0, 4, 5]), 'utf8', function(err) {         if (err) throw err;         console.log("the lines have been removed.");     }); })