Add check for parameters with a value of null or undefined

Author: dom-baur

src/lib/string.spec.ts

@@ -122,27 +122,28 @@ describe("string tests", () => {
   });
 
   test.each([
-    ["", " ", ""],
-    ["", "", ""],
-    ["hello world", "", "hello world"],
+    [null as unknown as string, " ", null as unknown as string],
+    [undefined as unknown as string, " ", undefined as unknown as string],
+    ["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 as unknown as string],
+    [undefined as unknown as string, " ", undefined as unknown as string],
     ["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 as unknown as string],
+    [undefined as unknown as string, " ", undefined as unknown as string],
     ["hello world", "", "hello world"],
     [" hello world ", " ", "hello world"],
   ])("trim", (haystack, needle, expected) => {

src/lib/string.ts

@@ -72,11 +72,12 @@ 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 {
-  const needleLength = needle.length;
-  if (needleLength === 0 || haystack.length === 0) {
+  if (isNullOrEmpty(haystack) || isNullOrEmpty(needle)) {
     return haystack;
   }
 
+  const needleLength = needle.length;
+
   let offset = 0;
 
   while (haystack.indexOf(needle, offset) === offset) {
@@ -92,13 +93,13 @@ export function ltrim(haystack: string, needle: string): string {
  * @returns the string trimmed from the right side
  */
 export function rtrim(haystack: string, needle: string): string {
-  const needleLength = needle.length,
-    haystackLength = haystack.length;
-
-  if (needleLength === 0 || haystackLength === 0) {
+  if (isNullOrEmpty(haystack) || isNullOrEmpty(needle)) {
     return haystack;
   }
 
+  const needleLength = needle.length,
+    haystackLength = haystack.length;
+
   let offset = haystackLength,
     idx = -1;