Detect return key in textarea and if a certain string is present write a line to textarea [javascript]

Question

Basically have a large textarea, and I want to be able to do a few things with it;

1. Detect when the user presses "enter" to go to a new line,

   and

2. When enter is pressed, if the line contains a certain string let's say "hello", a line would be written to the textarea that reads "hello to you."

I cannot, for the life of me, detect a string from within a textarea. I am a huge newb, though.

Much obliged.

Answer 1

I would use a JavaScript framework like jQuery for this purpose. The code would look something like this:

$(function() {
    $('textarea').keypress(function(event) {
        if (event.which == 13) { // Return key
            var textareaText = $(this).val();
            if (textareaText.match(/hello/)) {
                $(this).val(textareaText+"\nhello to you.");
            }
        }
    });
});