Question

I wrote a script for some text manipulation, and want to add a function so that the first line of my input string is removed if it starts with the symbol ‘>’. I tried to find a solution for hours now, but I cannot get it to work: Somehow the first line is not removed properly.

My input text should be processed as it is if it looks like this:
“HABHHIKKLLMMNMNIL”
and the first line should be removed if it looks like this:
“

>some text
HABHHIKKLLMMNMNIL

“

My current solution would look like this:

// remove first line if starts with '>'


if (sequence_str.substring(0) === '>'){
    // break the textblock into an array of lines
    var lines = sequence_str.split('\n');
    // remove one line, starting at the first position
    lines.splice(0,1);
    // join the array back into a single string
    var sequence_str = lines.join('\n');
}

sequence_str = sequence_str.replace(/(\r\n|\n|\r)/gm,""); //remove linebreaks

I would appreciate any ideas, and I hope some could help me to figure out where the problem is.

Thanks!

Answer 1

Why not just this?

sequence_str = sequence_str.replace(/^>.*/,'');

This will remove the first line if it starts with >. It will leave an empty line (the newline character is unaffected), but since you’re later stripping all line-breaks, it doesn’t matter.