NodeJS, fs.readFileSync string-by-string reading, and operating. How?

Question

Sorry for so dumb question,

How i can in NodeJS read from file string by string some value, for example - url, and do operation with each string eventually?

var contents = fs.readFileSync('test.txt', 'utf8');

and what then?

It's need for browserstack+selenium testing. I want run some links one-by-one, from file and do something with them.

Changed code below: from

console.log(lines[i++])

to

line = (lines[i++])
driver.get(line);
driver.getCurrentUrl()
                .then(function(currentUrl) {
                   console.log(currentUrl);

But it works once.

And

var str=fs.readFileSync('test.txt');
str.split(/\n/).forEach(function(line){})


C:\nodejstest>node test1.js
C:\nodejstest\test1.js:57
str.split(/\n/).forEach(function(line){
    ^

TypeError: str.split is not a function
    at Object.<anonymous> (C:\nodejstest\test1.js:57:5)
    at Module._compile (module.js:413:34)
    at Object.Module._extensions..js (module.js:422:10)
    at Module.load (module.js:357:32)
    at Function.Module._load (module.js:314:12)
    at Function.Module.runMain (module.js:447:10)
    at startup (node.js:142:18)
    at node.js:939:3

Works! Much thanx!

what do you mean string by string??? is it one word at a time or one line at a time!! — vkstack, Mar 28 '16 at 18:23

Rob Raisch · Accepted Answer · 2016-09-02T16:43:54.490

11

Another (simpler) method would be to read the entire file into a buffer, convert it to a string, split the string on your line-terminator to produce an array of lines, and then iterate over the array, as in:

var buf=fs.readFileSync(filepath);

buf.toString().split(/\n/).forEach(function(line){
  // do something here with each line
});

edited Sep 02 '16 at 16:43

answered Mar 28 '16 at 21:03

Rob Raisch

15,416
3
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vkstack · Answer 2 · 2016-03-28T19:36:01.673

0

read file with readable stream and do your operation when you find '\n'.

var fs=require('fs');
var readable = fs.createReadStream("data.txt", {
    encoding: 'utf8',
    fd: null
});
var lines=[];//this is array not a string!!!
readable.on('readable', function() {
    var chunk,tmp='';
    while (null !== (chunk = readable.read(1))) {
        if(chunk==='\n'){
            lines.push(tmp);
            tmp='';
        //    this is how i store each line in lines array
        }else
            tmp+=chunk;
    }
});
// readable.on('end',function(){
//     console.log(lines);    
// });
readable.on('end',function(){
    var i=0,len=lines.length;
    //lines is #array not string
    while(i<len)
        console.log(lines[i++]);
});

See if it works for you.

edited Mar 28 '16 at 19:36

answered Mar 28 '16 at 18:34

vkstack

1,484
9
21

what do you want to ask? – vkstack Mar 28 '16 at 19:09
How to make output look like http://url.com \n http://url2.su ? and do something with them one-by-one? – Boris Mar 28 '16 at 19:18
you wanna skip \r? btw how does it look like currently?? – vkstack Mar 28 '16 at 19:21
all symbols, like [, and ' – Boris Mar 28 '16 at 19:31
you can see.... lines is not a string ... that's an array of length = number of lines in the file!!!! – vkstack Mar 28 '16 at 19:33

NodeJS, fs.readFileSync string-by-string reading, and operating. How?

2 Answers2