Delete trailing newline character from pasted text

src/matrix.test.ts

@@ -65,6 +65,13 @@ describe("Matrix.split()", () => {
     expect(Matrix.split(CSV, Number)).toEqual(EXAMPLE_MATRIX);
   });
 
+  const CSVWithTrailingNewline = `${CSV}\n`;
+  test("Constructs a matrix from a CSV string with trailing newline", () => {
+    expect(Matrix.split(CSVWithTrailingNewline, Number)).toEqual(
+      EXAMPLE_MATRIX
+    );
+  });
+
   test("Keeps line breaks inside double quotes", () => {
     const csv = '"Value\n1"\tValue2\t"Value\n3"';
     const result = Matrix.split(csv, (value) => value);

src/matrix.ts

@@ -167,18 +167,29 @@ export function split<T>(
   horizontalSeparator = "\t",
   verticalSeparator: string | RegExp = /\r\n|\n|\r/
 ): Matrix<T> {
+  const verticalSeparatorRegExp =
+    typeof verticalSeparator === "string"
+      ? new RegExp(verticalSeparator)
+      : verticalSeparator;
+
   // Temporarily replace line breaks inside quotes
   const replaced = csv.replace(/"([^"]*?)"/g, (match, p1) => {
     return p1.replace(/\n/g, "\\n");
   });
-  return replaced.split(verticalSeparator).map((row) =>
-    row
-      .split(horizontalSeparator)
-      .map((line) => {
-        // Restore original line breaks in each line
-        return line.replace(/\\n/g, "\n");
-      })
-      .map(transform)
+  return (
+    replaced
+      // delete trailing new line character
+      .replace(new RegExp(`(${verticalSeparatorRegExp.source})$`), "")
+      .split(verticalSeparatorRegExp)
+      .map((row) =>
+        row
+          .split(horizontalSeparator)
+          .map((line) => {
+            // Restore original line breaks in each line
+            return line.replace(/\\n/g, "\n");
+          })
+          .map(transform)
+      )
   );
 }