I am trying to open a file with read permissions
var namestart=fso.OpenTextFile("C:\\name.txt",1);
var name2=namestart.ReadAll();
namestart.Close();
But this file is not always filled with something, ReadAll gives an error when the file is empty because (of course) it cannot read what's in the file and returns an error. Is there any way I can catch this error?
var namestart=fso.OpenTextFile("C:\\naam.txt",1);
var name2="";
if(namestart.ReadAll() != ""){
name2=namestart.ReadAll();
}
namestart.Close();
That doesn't work either as ReadAll returns an error.
You can use AtEndOfStream Property.
var namestart=fso.OpenTextFile("C:\\name.txt",1);
var name2 = namestart.AtEndOfStream ? "" : namestart.ReadAll();
namestart.Close();
You can check the .Size of the (existing) file or use try/catch to deal with not existing (as in the code below) and zero-length files.
var oFS = new ActiveXObject("Scripting.FileSystemObject");
var aFiles = ".\\25057783.js .\\empty.txt .\\nothere.nix".split(/ /);
for (var iFile in aFiles) {
var sFile = aFiles[iFile];
WScript.Echo("----", sFile)
try {
var oFile = oFS.GetFile(sFile);
if (0 < oFile.Size) {
var sContent = oFile.OpenAsTextStream().ReadAll();
WScript.Echo(" got content")
} else {
WScript.Echo(" file is empty");
}
}
catch(e) {
WScript.Echo(" Bingo:", e.message);
}
}
output:
cscript 25057783.js
---- .\25057783.js
got content
---- .\empty.txt
file is empty
---- .\nothere.nix
Bingo: File not found
Related
I am trying to extract pdf data to json format like below using in adobe pdf extract api,
this is the json I am getting
I want it to be something like this
Tried lots of solution with nested approach but can't figure out a proper way.
I have tried a nested approach but it didn't give proper solution
here is code
`
const fs = require("fs");
// Read the JSON file
const jsonString = fs.readFileSync("structuredData.json", "utf8");
// Parse the JSON string into an object
const data = JSON.parse(jsonString);
// Initialize the output object
const output = {};
// Loop through each line in the data
data.elements.forEach((line) => {
// Get the path and text values
const path = line.Path;
const text = line.Text;
// Split the path into an array
const pathParts = path.split("/");
// Initialize the current object to be the output object
let current = output;
let prev = null;
// Loop through each part of the path
pathParts.forEach((part, index) => {
// If this is the last part of the path, set the text as the value
if (index === pathParts.length - 1) {
if (Object.keys(current)[0]) {
prevdata = current[Object.keys(current)[0]];
current[Object.keys(current)[0]] = { ...prevdata, [text]: {} };
} else [(current[text] = {})];
} else {
// If the current object doesn't have a property with this path part, create it
if (!current[part]) {
current[part] = {};
}
// Set the current object to be the nested object
current = current[part];
}
});
});
// Convert the output object to a JSON string and write it to a file
fs.writeFileSync("output.json", JSON.stringify(output));
`
I am creating an application with Node.js and I am trying to read a file called "datalog.txt." I use the "append" function to write to the file:
//Appends buffer data to a given file
function append(filename, buffer) {
let fd = fs.openSync(filename, 'a+');
fs.writeSync(fd, str2ab(buffer));
fs.closeSync(fd);
}
//Converts string to buffer
function str2ab(str) {
var buf = new ArrayBuffer(str.length*2); // 2 bytes for each char
var bufView = new Uint16Array(buf);
for (var i=0, strLen=str.length; i < strLen; i++) {
bufView[i] = str.charCodeAt(i);
}
return buf;
}
append("datalog.txt","12345");
This seems to work great. However, now I want to use fs.readFileSync to read from the file. I tried using this:
const data = fs.readFileSync('datalog.txt', 'utf16le');
I changed the encoding parameter to all of the encoding types listed in the Node documentation, but all of them resulted in this error:
TypeError: Argument at index 2 is invalid: Invalid encoding
All I want to be able to do is be able to read the data from "datalog.txt." Any help would be greatly appreciated!
NOTE: Once I can read the data of the file, I want to be able to get a list of all the lines of the file.
Encoding and type are an object:
const data = fs.readFileSync('datalog.txt', {encoding:'utf16le'});
Okay, after a few hours of troubleshooting a looking at the docs I figured out a way to do this.
try {
// get metadata on the file (we need the file size)
let fileData = fs.statSync("datalog.txt");
// create ArrayBuffer to hold the file contents
let dataBuffer = new ArrayBuffer(fileData["size"]);
// read the contents of the file into the ArrayBuffer
fs.readSync(fs.openSync("datalog.txt", 'r'), dataBuffer, 0, fileData["size"], 0);
// convert the ArrayBuffer into a string
let data = String.fromCharCode.apply(null, new Uint16Array(dataBuffer));
// split the contents into lines
let dataLines = data.split(/\r?\n/);
// print out each line
dataLines.forEach((line) => {
console.log(line);
});
} catch (err) {
console.error(err);
}
Hope it helps someone else with the same problem!
This works for me:
index.js
const fs = require('fs');
// Write
fs.writeFileSync('./customfile.txt', 'Content_For_Writing');
// Read
const file_content = fs.readFileSync('./customfile.txt', {encoding:'utf8'}).toString();
console.log(file_content);
node index.js
Output:
Content_For_Writing
Process finished with exit code 0
I want to use Node.js to create a simple logging system which prints a line before the past line into a .txt file. However, I don't know how the file system functionality from Node.js works.
Can someone explain it?
Inserting data into the middle of a text file is not a simple task. If possible, you should append it to the end of your file.
The easiest way to append data some text file is to use build-in fs.appendFile(filename, data[, options], callback) function from fs module:
var fs = require('fs')
fs.appendFile('log.txt', 'new data', function (err) {
if (err) {
// append failed
} else {
// done
}
})
But if you want to write data to log file several times, then it'll be best to use fs.createWriteStream(path[, options]) function instead:
var fs = require('fs')
var logger = fs.createWriteStream('log.txt', {
flags: 'a' // 'a' means appending (old data will be preserved)
})
logger.write('some data') // append string to your file
logger.write('more data') // again
logger.write('and more') // again
Node will keep appending new data to your file every time you'll call .write, until your application will be closed, or until you'll manually close the stream calling .end:
logger.end() // close string
Note that logger.write in the above example does not write to a new line. To write data to a new line:
var writeLine = (line) => logger.write(`\n${line}`);
writeLine('Data written to a new line');
Simply use fs module and something like this:
fs.appendFile('server.log', 'string to append', function (err) {
if (err) return console.log(err);
console.log('Appended!');
});
Step 1
If you have a small file
Read all the file data in to memory
Step 2
Convert file data string into Array
Step 3
Search the array to find a location where you want to insert the text
Step 4
Once you have the location insert your text
yourArray.splice(index,0,"new added test");
Step 5
convert your array to string
yourArray.join("");
Step 6
write your file like so
fs.createWriteStream(yourArray);
This is not advised if your file is too big
I created a log file which prints data into text file using "Winston" logger. The source code is here below,
const { createLogger, format, transports } = require('winston');
var fs = require('fs')
var logger = fs.createWriteStream('Data Log.txt', {
flags: 'a'
})
const os = require('os');
var sleep = require('system-sleep');
var endOfLine = require('os').EOL;
var t = ' ';
var s = ' ';
var q = ' ';
var array1=[];
var array2=[];
var array3=[];
var array4=[];
array1[0] = 78;
array1[1] = 56;
array1[2] = 24;
array1[3] = 34;
for (var n=0;n<4;n++)
{
array2[n]=array1[n].toString();
}
for (var k=0;k<4;k++)
{
array3[k]=Buffer.from(' ');
}
for (var a=0;a<4;a++)
{
array4[a]=Buffer.from(array2[a]);
}
for (m=0;m<4;m++)
{
array4[m].copy(array3[m],0);
}
logger.write('Date'+q);
logger.write('Time'+(q+' '))
logger.write('Data 01'+t);
logger.write('Data 02'+t);
logger.write('Data 03'+t);
logger.write('Data 04'+t)
logger.write(endOfLine);
logger.write(endOfLine);
function mydata() //user defined function
{
logger.write(datechar+s);
logger.write(timechar+s);
for ( n = 0; n < 4; n++)
{
logger.write(array3[n]);
}
logger.write(endOfLine);
}
var now = new Date();
var dateFormat = require('dateformat');
var date = dateFormat(now,"isoDate");
var time = dateFormat(now, "h:MM:ss TT ");
var datechar = date.toString();
var timechar = time.toString();
mydata();
sleep(5*1000);
i have a small problem, when i try to copy one file from my tmp dir to my ftp dir the writen file is empty. I have no error, i don't understand what i'm doing wrong
var ftpPath = "/var/www/ftp/",
zipPath = "/var/www/tmp/",
file = "test";
fs.createReadStream(zipPath + file).pipe(fs.createWriteStream(ftpPath + file));
My test file contain loremipsum sample.
If you have any solution, i take it, this is the only line that bug in my app :(
First, make sure that the file /var/www/tmp/test exists, is a file, and has the right permissions for the user you start the script with.
Second, make sure that /var/www/ftp/ has writing permissions.
Then the following code should work :
var readerStream = fs.createReadStream('/var/www/tmp/test');
var writerStream = fs.createWriteStream('/var/www/ftp/test');
readerStream.pipe(writerStream);
Edit :
try debugging using this snippet :
var data;
var readerStream = fs.createReadStream('/var/www/tmp/test');
readerStream.on('data', function(data) {
data += data;
});
readerStream.on('end', function() {
console.log(data);
});
I need to open an existing JavaScript file, check if this string exists:
var LocalStrategy = require('passport-local').Strategy;
If it doesn't, then append it at the top with the rest of require() lines.
In another case, I need to check if that string exists, and if it does, I would like to remove just that line.
I have looked at fs.readFile, fs.writeFile, fs.open but I don't think it is capable of doing what I need. Any suggestions?
This is a simplified script:
var fs = require('fs');
var search = "var LocalStrategy = require('passport-local').Strategy;";
function append (line) {
line = line || 0;
var body = fs.readFileSync('example.js').toString();
if (body.indexOf(search) < 0 ) {
body = body.split('\n');
body.splice(line + 1,0,search);
body = body.filter(function(str){ return str; }); // remove empty lines
var output = body.join('\n');
fs.writeFileSync('example.js', output);
}
}
function remove () {
var body = fs.readFileSync('example.js').toString();
var idx = body.indexOf(search);
if (idx >= 0 ) {
var output = body.substr(0, idx) + body.substr(idx + search.length);
fs.writeFileSync('example.js', output);
}
}