add string utilities

Author: piotrkulpinski

package.json

@@ -1,7 +1,7 @@
 {
   "name": "@curiousleaf/utils",
   "description": "A lightweight set of utilities",
-  "version": "1.1.3",
+  "version": "1.1.4",
   "license": "MIT",
   "type": "module",
   "author": {

src/string/string.test.ts

@@ -0,0 +1,56 @@
+import { describe, expect, test } from "bun:test"
+import { lcFirst, ucFirst } from "./string"
+
+describe("ucFirst", () => {
+  test("should uppercase the first character of a string", () => {
+    expect(ucFirst("hello")).toBe("Hello")
+    expect(ucFirst("world")).toBe("World")
+  })
+
+  test("should handle empty strings", () => {
+    expect(ucFirst("")).toBe("")
+  })
+
+  test("should handle single character strings", () => {
+    expect(ucFirst("a")).toBe("A")
+    expect(ucFirst("z")).toBe("Z")
+  })
+
+  test("should handle non-string inputs", () => {
+    expect(ucFirst(null as any)).toBe("")
+    expect(ucFirst(undefined as any)).toBe("")
+    expect(ucFirst(123 as any)).toBe("")
+  })
+
+  test("should preserve the rest of the string", () => {
+    expect(ucFirst("hello world")).toBe("Hello world")
+    expect(ucFirst("HELLO")).toBe("HELLO")
+  })
+})
+
+describe("lcFirst", () => {
+  test("should lowercase the first character of a string", () => {
+    expect(lcFirst("Hello")).toBe("hello")
+    expect(lcFirst("World")).toBe("world")
+  })
+
+  test("should handle empty strings", () => {
+    expect(lcFirst("")).toBe("")
+  })
+
+  test("should handle single character strings", () => {
+    expect(lcFirst("A")).toBe("a")
+    expect(lcFirst("Z")).toBe("z")
+  })
+
+  test("should handle non-string inputs", () => {
+    expect(lcFirst(null as any)).toBe("")
+    expect(lcFirst(undefined as any)).toBe("")
+    expect(lcFirst(123 as any)).toBe("")
+  })
+
+  test("should preserve the rest of the string", () => {
+    expect(lcFirst("Hello World")).toBe("hello World")
+    expect(lcFirst("hello")).toBe("hello")
+  })
+})

src/string/string.ts

@@ -0,0 +1,37 @@
+/**
+ * Utility functions for working with strings.
+ */
+
+/**
+ * Uppercases the first character in the `string`.
+ * @param string - The string to uppercase the first character of.
+ * @returns The string with the first character in uppercase.
+ */
+export const ucFirst = (string: string) => {
+  if (typeof string !== "string") {
+    return ""
+  }
+
+  if (string.length === 0) {
+    return string
+  }
+
+  return string[0]?.toUpperCase() + string.slice(1)
+}
+
+/**
+ * Lowercases the first character in the `string`.
+ * @param string - The string to lowercase the first character of.
+ * @returns The string with the first character in lowercase.
+ */
+export const lcFirst = (string: string) => {
+  if (typeof string !== "string") {
+    return ""
+  }
+
+  if (string.length === 0) {
+    return string
+  }
+
+  return string[0]?.toLowerCase() + string.slice(1)
+}