remove multi-lines in text

How do I r开发者_JS百科emove line 1,2,3 and retain line 4?

Like:

1. Programmer
2. Business Owner
3. Manager
4. Marketer

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you can split on linebreaks (\r and \n), then grab the last element:

textfield.text = textfield.text.split(/[\r\n]/gm).pop();