Fix string utility functions ltrim, rtrim null check

Author: dom-baur

src/lib/string.spec.ts

@@ -122,65 +122,33 @@ describe("string tests", () => {
   });
 
   test.each([
-    [null as unknown as string, " ", null],
-    [undefined as unknown as string, " ", undefined],
+    ["", " ", ""],
+    ["", "", ""],
+    ["hello world", "", "hello world"],
     [" hello world", " ", "hello world"],
-    ["  hello world", " ", "hello world"],
-    ["   hello world", " ", "hello world"],
   ])("left trim", (haystack, needle, expected) => {
     expect(ltrim(haystack, needle)).toBe(expected);
   });
 
   test.each([
-    [null as unknown as string, " ", null],
-    [undefined as unknown as string, " ", undefined],
-    [" hello world", "", " hello world"],
-    ["  hello world", "", "  hello world"],
-    ["   hello world", "", "   hello world"],
-  ])("left trim without needle", (haystack, needle, expected) => {
-    expect(ltrim(haystack, needle)).toBe(expected);
-  });
-
-  test.each([
-    [null as unknown as string, " ", null],
-    [undefined as unknown as string, " ", undefined],
+    ["", " ", ""],
+    ["", "", ""],
+    ["hello world", "hello world", ""],
+    ["hello world", "", "hello world"],
     ["hello world ", " ", "hello world"],
-    ["hello world  ", " ", "hello world"],
-    ["hello world   ", " ", "hello world"],
   ])("right trim", (haystack, needle, expected) => {
     expect(rtrim(haystack, needle)).toBe(expected);
   });
 
   test.each([
-    [null as unknown as string, " ", null],
-    [undefined as unknown as string, " ", undefined],
-    ["hello world ", "", "hello world "],
-    ["hello world  ", "", "hello world  "],
-    ["hello world   ", "", "hello world   "],
-  ])("right trim without needle", (haystack, needle, expected) => {
-    expect(rtrim(haystack, needle)).toBe(expected);
-  });
-
-  test.each([
-    [null as unknown as string, " ", null],
-    [undefined as unknown as string, " ", undefined],
+    ["", " ", ""],
+    ["", "", ""],
+    ["hello world", "", "hello world"],
     [" hello world ", " ", "hello world"],
-    ["  hello world  ", " ", "hello world"],
-    ["   hello world   ", " ", "hello world"],
   ])("trim", (haystack, needle, expected) => {
     expect(trim(haystack, needle)).toBe(expected);
   });
 
-  test.each([
-    [null as unknown as string, " ", null],
-    [undefined as unknown as string, " ", undefined],
-    [" hello world ", "", " hello world "],
-    ["  hello world  ", "", "  hello world  "],
-    ["   hello world   ", "", "   hello world   "],
-  ])("trim without needle", (haystack, needle, expected) => {
-    expect(trim(haystack, needle)).toBe(expected);
-  });
-
   test.each([["hello world", ["hello world"]]])("splitLine with single line", (str, expected) => {
     expect(splitLine(str)).toStrictEqual(expected);
   });

src/lib/string.ts

@@ -72,8 +72,6 @@ export function truncate(value: string | undefined, maxLength: number, suffix =
  * @returns the string trimmed from the left side
  */
 export function ltrim(haystack: string, needle: string): string {
-  if (!haystack || !needle) return haystack;
-
   const needleLength = needle.length;
   if (needleLength === 0 || haystack.length === 0) {
     return haystack;
@@ -94,18 +92,14 @@ export function ltrim(haystack: string, needle: string): string {
  * @returns the string trimmed from the right side
  */
 export function rtrim(haystack: string, needle: string): string {
-  if (!haystack || !needle) {
-    return haystack;
-  }
-
   const needleLength = needle.length,
-    haystackLen = haystack.length;
+    haystackLength = haystack.length;
 
-  if (needleLength === 0 || haystackLen === 0) {
+  if (needleLength === 0 || haystackLength === 0) {
     return haystack;
   }
 
-  let offset = haystackLen,
+  let offset = haystackLength,
     idx = -1;
 
   while (true) {