文件。行与我的JFile包

伪

var JFile=require('jfile');

var myF=new JFile("./data.txt");
myF.lines // ["first line","second line"] ....

不要忘记之前:

npm install jfile --save

另一个答案是使用npm包。nexline包允许用户逐行异步读取文件:

"use strict";

import fs from 'fs';
import nexline from 'nexline';

const lines = [];
const reader = nexline({
    input: fs.createReadStream(`path/to/file.ext`)
});

while(true) {
    const line = await reader.next();
    if(line === null) break; // line is null if we reach the end
    if(line.length === 0) continue; // Ignore empty lines
    
    // Process the line here - below is just an example
    lines.push(line);
}

即使您的文本文件大于允许的最大字符串长度，这种方法也可以工作，从而避免“错误:不能创建超过0x1fffffe8个字符的字符串”错误。

使用Node.js的readline模块。

var fs = require('fs');
var readline = require('readline');

var filename = process.argv[2];
readline.createInterface({
    input: fs.createReadStream(filename),
    terminal: false
}).on('line', function(line) {
   console.log('Line: ' + line);
});

要将一个大文件读入数组，您可以逐行或逐块读取。

一行一行的参考我这里的答案

var fs = require('fs'),
    es = require('event-stream'),

var lines = [];

var s = fs.createReadStream('filepath')
    .pipe(es.split())
    .pipe(es.mapSync(function(line) {
        //pause the readstream
        s.pause();
        lines.push(line);
        s.resume();
    })
    .on('error', function(err) {
        console.log('Error:', err);
    })
    .on('end', function() {
        console.log('Finish reading.');
        console.log(lines);
    })
);

一块一块的参考本文

var offset = 0;
var chunkSize = 2048;
var chunkBuffer = new Buffer(chunkSize);
var fp = fs.openSync('filepath', 'r');
var bytesRead = 0;
while(bytesRead = fs.readSync(fp, chunkBuffer, 0, chunkSize, offset)) {
    offset += bytesRead;
    var str = chunkBuffer.slice(0, bytesRead).toString();
    var arr = str.split('\n');

    if(bytesRead = chunkSize) {
        // the last item of the arr may be not a full line, leave it to the next chunk
        offset -= arr.pop().length;
    }
    lines.push(arr);
}
console.log(lines);

如果你能把最终的数据放入一个数组，那么你不也能把它放入一个字符串中并分割它吗? 在任何情况下，如果你想一次处理一行文件，你也可以尝试这样做:

var fs = require('fs');

function readLines(input, func) {
  var remaining = '';

  input.on('data', function(data) {
    remaining += data;
    var index = remaining.indexOf('\n');
    while (index > -1) {
      var line = remaining.substring(0, index);
      remaining = remaining.substring(index + 1);
      func(line);
      index = remaining.indexOf('\n');
    }
  });

  input.on('end', function() {
    if (remaining.length > 0) {
      func(remaining);
    }
  });
}

function func(data) {
  console.log('Line: ' + data);
}

var input = fs.createReadStream('lines.txt');
readLines(input, func);

编辑:(回应phopkins的评论)我认为(至少在新版本中)substring不复制数据，而是创建一个特殊的SlicedString对象(从v8源代码中快速浏览)。在任何情况下，这里有一个修改，避免了提到的子字符串(在一个文件上测试了几个兆字节的“只工作不玩耍，聪明的孩子会变傻”):

function readLines(input, func) {
  var remaining = '';

  input.on('data', function(data) {
    remaining += data;
    var index = remaining.indexOf('\n');
    var last  = 0;
    while (index > -1) {
      var line = remaining.substring(last, index);
      last = index + 1;
      func(line);
      index = remaining.indexOf('\n', last);
    }

    remaining = remaining.substring(last);
  });

  input.on('end', function() {
    if (remaining.length > 0) {
      func(remaining);
    }
  });
}

js:

var array = fs.readFileSync('file.txt', 'utf8').split('\n');

ts:

var array = fs.readFileSync('file.txt', 'utf8').toString().split('\n');