Reference · Strings

starts_with

starts_with(str, str) -> bool

What it does

Whether the text begins with a prefix. The comparison is exact: case matters and the prefix is plain text, not a pattern.

Examples

print(starts_with("hello", "he"), starts_with("hello", "He"))print(starts_with("/api/users", "/api/"))

true falsetrue

Edge cases

• Every string starts with "", the empty string included.
• A string starts with itself; a prefix longer than the text is false.
• Characters, not bytes: starts_with("héllo", "hé") is true.

print(starts_with("hello", ""), starts_with("", ""))print(starts_with("hello", "hello"), starts_with("hello", "hellos"))print(starts_with("héllo", "hé"))

true truetrue falsetrue

Errors

An argument that is not a string, on either side, is a runtime error, not an error value: null and numbers are refused. Give a null field ?? "" first.

print(starts_with("abc", 1))

line 1: `starts_with` expects a str as argument 2, got int

Chaining

In a pipeline the text comes first and the prefix is the argument:

print("Hello" | starts_with("H"))print(["/api/a", "/web", "/api/b"] | filter((p) => p | starts_with("/api/")))print(("Hello" | starts_with("H")) && ("Hello" | ends_with("o")))

true["/api/a", "/api/b"]true

See also

ends_with, contains, index_of, slice, re.test

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