JavaScript：修改多行输入的内容

Question

I have a multi-line input box and I'm trying to output to another text box using document.getElementById('output').value when the button on the form is pressed.

Basically what I want to do is wrap [img] tags around every line. Which function do I use to do this? I have googled this to death but I can't find anything explaining it.

eg.

input of:
picture1.jpg
picture2.jpg
picture2.jpg

outputs to:
[img]picture1.jpg[/img]
[img]picture2.jpg[/img]
[img]picture2.jpg[/img]

I've set this up to make it easier for help:

<SCRIPT LANGUAGE="JavaScript">
function testResults (form) {
    var Images = form.images.value;

    document.getElementById('output').value = Images;       

}
</SCRIPT>
<form name="form" method="post" action="">
  <textarea name="images" cols="40" rows="10" id="images"></textarea>
<br>
<br>
<INPUT TYPE="button" NAME="button" Value="[IMG]" onClick="testResults(this.form)">
<br>
<br>
<label>
<textarea name="output" id="output" cols="40" rows="10"></textarea>
</label>
</form>

Answer 1

Try something like:

data = data.split('\n')
    .map(function (line) {
        return '[img]' + line + '[/img]';
    })
    .join('\n');