In nodejs is it possible to detect multiple occurrences of the same string in a txt file?
My current code is as below
const fs = require('fs');
var file_path = 'file.txt';
fs.readFile(file_path, "UTF-8", (error, data) => {
if (error) throw error;
else {
if (data.includes('Test Value')) {
console.log(data.indexOf('Test Value'))
}
fs.close(file, (err) => {
if (err)
console.error('Failed to close file', err);
else {
console.log("\n> File Closed successfully");
}
});
}
});
In file.txt, I have below contents
Value1
Value2
Test Value
Value3
Test Value
Value4
when I run the above code, I could only detect first occurrence of 'Test Value' whereas I need to detect all occurrences of 'Test Value' in file.txt, please help
indexOf has two parameters. You can use store the last position and continue the next search at the next position:
const fs = require('fs');
var file_path = 'file.txt';
fs.readFile(file_path, "UTF-8", (error, data) => {
if (error) throw error;
else {
for (let pos = data.indexOf('Test Value'); pos > -1; pos = data.indexOf('Test Value', pos + 1)) {
console.log(pos);
}
fs.close(file, (err) => {
if (err)
console.error('Failed to close file', err);
else {
console.log("\n> File Closed successfully");
}
});
}
});
Example:
const data = `Value1
Value2
Test Value
Value3
Test Value
Value4`;
for (let pos = data.indexOf('Test Value'); pos > -1; pos = data.indexOf('Test Value', pos + 1)) {
console.log(pos);
}You can use a regexp global search (multiple matches) with the RegExp .exec() method.
A global search using the String .match() method returns just the matches without the index. However the RegExp .exec() method returns the index.
let match;
let search = /Test Value/g; // <-- the 'g' flag is important!
// If you need to construct the regexp dynamically
// do = new RegExp('Test Value', 'g')
while (match = search.exec(data)) {
console.log(match.index);
}
Yes. Loop through the data array and check each data element.
const fs = require('fs');
var file_path = 'file.txt';
fs.readFile(file_path, "UTF-8", (error, data) => {
if (error) throw error;
else {
data.split('\n').forEach(line => {
if (line === 'Test Value') {
console.log(data.indexOf(line))
}
})
fs.close(file, (err) => {
if (err)
console.error('Failed to close file', err);
else {
console.log("\n> File Closed successfully");
}
});
}
});