✨ Add validator for isTrimmable and such function

deps.ts

@@ -14,6 +14,9 @@ export {
   not,
   or,
   pipe,
+  trim,
+  trimLeft,
+  trimRight,
   tryCatch,
 } from "https://deno.land/x/fonction@v1.8.1/mod.ts";
 

validation/isTrimmable.ts

@@ -0,0 +1,49 @@
+// Copyright 2021-present the is-valid authors. All rights reserved. MIT license.
+import { trim, trimLeft, trimRight } from "../deps.ts";
+
+/**
+ * Whatever val is trimmable or not.
+ *
+ * @param val - Any `string`
+ * @returns The result of `trim(val) !== val`
+ *
+ * @example
+ * ```ts
+ * isTrimmable(' test') // true
+ * isTrimmable('test ') // true
+ * isTrimmable(' test ') // true
+ * ```
+ */
+const isTrimmable = (val: string) => trim(val) !== val;
+
+/**
+ * Whatever val is left side trimmable or not.
+ *
+ * @param val - Any `string`
+ * @returns The result of `trimLeft(val) !== val`
+ *
+ * @example
+ * ```ts
+ * isLeftTrimmable('test ') // false
+ * isLeftTrimmable(' test') // true
+ * isLeftTrimmable(' test ') // true
+ * ```
+ */
+const isLeftTrimmable = (val: string) => trimLeft(val) !== val;
+
+/**
+ * Whatever val is right side trimmable or not.
+ *
+ * @param val - Any `string`
+ * @returns The result of `trimRight(val) !== val`
+ *
+ * @example
+ * ```ts
+ * isRightTrimmable(' test') // false
+ * isRightTrimmable('test ') // true
+ * isRightTrimmable(' test ') // true
+ * ```
+ */
+const isRightTrimmable = (val: string) => trimRight(val) !== val;
+
+export { isLeftTrimmable, isRightTrimmable, isTrimmable };

validation/isTrimmable_test.ts

@@ -0,0 +1,65 @@
+// Copyright 2021-present the is-valid authors. All rights reserved. MIT license.
+
+import { assertEquals } from "../dev_deps.ts";
+import {
+  isLeftTrimmable,
+  isRightTrimmable,
+  isTrimmable,
+} from "./isTrimmable.ts";
+
+Deno.test("isTrimmable", () => {
+  const table: [string, boolean][] = [
+    ["", false],
+    ["a", false],
+    ["hoge", false],
+    [" hoge", true],
+    ["hoge ", true],
+    [" hoge ", true],
+  ];
+
+  table.forEach(([val, expected]) => {
+    assertEquals(
+      isTrimmable(val),
+      expected,
+      `isTrimmable(${val}) -> ${expected}`,
+    );
+  });
+});
+
+Deno.test("isLeftTrimmable", () => {
+  const table: [string, boolean][] = [
+    ["", false],
+    ["a", false],
+    ["hoge", false],
+    [" hoge", true],
+    ["hoge ", false],
+    [" hoge ", true],
+  ];
+
+  table.forEach(([val, expected]) => {
+    assertEquals(
+      isLeftTrimmable(val),
+      expected,
+      `isLeftTrimmable(${val}) -> ${expected}`,
+    );
+  });
+});
+
+Deno.test("isRightTrimmable", () => {
+  const table: [string, boolean][] = [
+    ["", false],
+    ["a", false],
+    ["hoge", false],
+    [" hoge", false],
+    ["hoge ", true],
+    [" hoge ", true],
+  ];
+
+  table.forEach(([val, expected]) => {
+    assertEquals(
+      isRightTrimmable(val),
+      expected,
+      `isRightTrimmable(${val}) -> ${expected}`,
+    );
+  });
+});

validation/mod.ts

@@ -17,3 +17,4 @@ export * from "./isSymbol.ts";
 export * from "./isUndefined.ts";
 export * from "./isLowerCase.ts";
 export * from "./isUpperCase.ts";
+export * from "./isTrimmable.ts";