Join Lines

In short Joining lines merges a multi-line list into one line using any separator, with optional quoting and wrapping. It is the inverse of splitting and it is used constantly by anyone who moves data between a spreadsheet and code. A column of values copied from a spreadsheet arrives as one value per line; joined with a comma it is a CSV row, joined with a comma and quoted it is an SQL IN clause or a JSON array, and joined with a space it is a sentence. The quoting option is what makes those cases work without hand-editing, because wrapping each item individually before joining is exactly what an SQL or JSON list needs and doing it by hand for two hundred values is not realistic. Two details that catch people. Trailing whitespace on each line comes along with it unless trimmed first, so the result is full of spaces before the separators — trim before joining. And an empty line in the middle produces an empty item, which in a JSON array or an SQL list is a value rather than nothing.