fix matching split returning list with Nil on JS

Author: PgBiel

src/gleam/regex.gleam

@@ -127,19 +127,10 @@ pub fn split(with regex: Regex, content string: String) -> List(String) {
   do_split(regex, string)
 }
 
-@target(erlang)
 @external(erlang, "gleam_stdlib", "regex_split")
+@external(javascript, "../gleam_stdlib.mjs", "regex_split")
 fn do_split(a: Regex, b: String) -> List(String)
 
-@target(javascript)
-fn do_split(regex, string) -> List(String) {
-  js_split(string, regex)
-}
-
-@target(javascript)
-@external(javascript, "../gleam_stdlib.mjs", "split")
-fn js_split(a: String, b: Regex) -> List(String)
-
 /// Collects all matches of the regular expression.
 ///
 /// ## Examples

src/gleam_stdlib.mjs

@@ -402,6 +402,10 @@ export function compile_regex(pattern, options) {
   }
 }
 
+export function regex_split(regex, string) {
+  return List.fromArray(string.split(regex).map(item => item === undefined ? "" : item));
+}
+
 export function regex_scan(regex, string) {
   const matches = Array.from(string.matchAll(regex)).map((match) => {
     const content = match[0];

test/gleam/regex_test.gleam

@@ -73,6 +73,15 @@ pub fn split_test() {
   |> should.equal(["foo", "32", "4", "9", "0"])
 }
 
+pub fn matching_split_test() {
+  let assert Ok(re) = regex.from_string("([+-])( *)(d)*")
+
+  regex.split(re, "abc+ def+ghi+  abc")
+  |> should.equal([
+    "abc", "+", " ", "d", "ef", "+", "", "", "ghi", "+", "  ", "", "abc",
+  ])
+}
+
 pub fn scan_test() {
   let assert Ok(re) = regex.from_string("Gl\\w+")