how to add a first line to a text file in node.js (using fs)

Question

I'm trying to add a first line to an existing text file using node.js.

My actual code looks as follows: var fs = require('fs');

fs.appendFile('test.txt', 'X        Y', function (err) {

});   

The text: 'X Y' is not added as first line, but last.

It would help a lot, if you have an idea, how to add my line as first of the document! :-)

Greetings, JS

Answer 1

You can't. The file systems are not designed that way. You have to write your line first to a temp file and then append the content of you file. Then rename/move your temp file to the name of the original one. (And be sure there was no error when writing, otherwise you loose the content of the original file.)