r-line
This node script is designed to allow quick and easy modification of text files.
For this purpose, the script offers a simple preview mode for the changes before they are applied.
It has no dependencies and can be integrated directly into your project even without npm.
Installation
npm install r-lineAlternatively, simply use the script from lib/r-line.js as standalone.
Sample usage
import rl from 'r-line';
rl.replaceLine('lib/r-line.js', (line) => {
if (line.includes('function preview(')) {
return line.replace('preview', 'foo'); // return string to change a line
}
if (line.includes('const stringUtils')) {
return false; // return "false" to delete a line
}
}, {dryRun: true});This leads to the following output:
[INFO] Preview: 'lib/r-line.js'
176 ┌ function preview(originalLines, changedLines, options) {
C └▷ function foo(originalLines, changedLines, options) {
337 D ┤ const stringUtils = {
If you remove dryRun: true, the changes will be applied.
Preview options
You can customise the preview with the following optional parameters:
rl.replaceLine('your/file.js', (line) => {
//
}, {
previewOptions: {
// Visualises whitespaces and tabs.
showSpaces: true / false, // default := false
// Previews the complete file content, not just the changed lines.
showUnchangedLines: true / false, // default := false
// Hides the original content of the changed lines.
hideOriginalLines: true / false, // default := false
// By default unnecessary indentation is removed.
// However, the behavior can be turned off.
keepOriginalIndentation: true / false // default := false
}
});Line context
The callback function provides a context object as the second parameter.
This contains the line number and previous or following lines.
rl.replaceLine('your/file.js', (line, context) => {
context.lineNumber; // number
context.next.line; // String
context.next.lines; // string[]
context.previous.line; // String
context.previous.lines; // string[]
});Listing files
If you are editing several files at once, then there is a helper function for this called listFiles.
rl.listFiles('lib', (file) => rl.replaceLine(file, (line) => {
//
}));