如何从txt文件中删除一行

Question

我有以下文本文件("test.txt"),我想在node.js中操作:

world
food

我想删除第一行,以便food成为第一行.我怎样才能做到这一点？

Answer 1

var fs = require('fs')
fs.readFile(filename, 'utf8', function(err, data)
{
    if (err)
    {
        // check and handle err
    }
    var linesExceptFirst = data.split('\n').slice(1).join('\n');
    fs.writeFile(filename, linesExceptFirst);
});

Answer 2

我刚刚遇到需要能够排除文件中的几行。这是我如何使用简单的节点函数来完成此操作。

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.");
    });
})

Answer 3

使用替换

const fs = require('fs');

function readWriteSync() {
  var data = fs.readFileSync(filepath, 'utf-8');

  // replace 'world' together with the new line character with empty
  var newValue = data.replace(/world\n/, '');

  fs.writeFileSync(filepath, newValue, 'utf-8');
}