CODEWITHSUNDEEP
javascript
Màh Di
Màh Di

Reputation: 13

Adding a word at the beginning of every line

I have a txt file with 20.000 lines, and I want to add a word at the beginning of every line. Example :
Original file
A
B
C
D
I want to make it look like this
Y A
Y B
Y C
Y D
Is there any solution with JavaScript code ?

Upvotes: 0

Views: 161

Answers (2)

p.s.w.g
p.s.w.g

Reputation: 149050

This should work:

var input = "A\nB\nC\nD";
var output = input.split("\n")
                  .map(function(s) { return "Y " + s; })
                  .join("\n");

But for 20,000 lines, this won't be terribly efficient. It's probably better if you can read the file one line at a time server side, and write the result to the output stream one line a time.

Also note, the map function was introduced in ES5, so it won't be available in some older browsers. You can polyfill it, or use this alternative suggested by gilly3:

var output = "Y " + input.split("\n").join("\nY ");

Upvotes: 1

twj
twj

Reputation: 767

A bit of regex:

str = 
'a\n'+
'b\n'+
'c\n'+
'd';

str.replace(/^/mg, 'prefix ')

/*
prefix a
prefix b
prefix c
prefix d
*/

Upvotes: 0

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