Replace and Trim

replace(what, with) returns a new string where every appearance of what is replaced with with. Replacing with an empty string removes the text:

var phone := "555-123-4567"
print(phone.replace("-", ""))
print(phone.replace("-", " "))
print(phone)

5551234567
555 123 4567
555-123-4567

The original string does not change. replace() is case-sensitive; replacen() does the same job and ignores case:

var chat := "Hello hello HELLO"
print(chat.replace("hello", "hi"))
print(chat.replacen("hello", "hi"))

Hello hi HELLO
hi hi hi

Text typed by a user often has extra spaces around it. strip_edges() removes spaces, tabs and line breaks from both ends and keeps the ones in the middle:

var typed := "   Ana Lee  "
print("[" + typed.strip_edges() + "]")

[Ana Lee]

strip_edges(true, false) trims only the left end and strip_edges(false, true) only the right end. To remove one specific text at an end, use trim_prefix() or trim_suffix(). They change nothing when the text is not there:

print("level_03.tscn".trim_suffix(".tscn"))
print("level_03.tscn".trim_suffix(".png"))

level_03
level_03.tscn

Each of these methods returns a string, so you can chain them: raw.strip_edges().to_lower().replace(" ", "_").