✨ Add B.join, B.isNil, B.instanceOf

src/index.ts

@@ -8,6 +8,9 @@ import every from './every'
 import F from './F'
 import functionalIf from './functionalIf'
 import functionalSwitch from './functionalSwitch'
+import instanceOf from './instanceOf'
+import isNil from './isNil'
+import join from './join'
 import multiply from './multiply'
 import not from './not'
 import nth from './nth'
@@ -34,6 +37,9 @@ export {
   every,
   functionalIf,
   functionalSwitch,
+  instanceOf,
+  isNil,
+  join,
   multiply,
   not,
   nth,

src/instanceOf.ts

@@ -0,0 +1,25 @@
+/**
+ * Test if the the second argument is an instance of the first argument. (curried)
+ * ```js
+ * instanceOf(Number)(new Number(1)) //=> true
+ * instanceOf(Number)(1) //=> false
+ * ```
+ */
+function instanceOf(a: any): (b: any) => boolean
+/**
+ * Test if the the second argument is an instance of the first argument.
+ * ```js
+ * instanceOf(Number, new Number(1)) //=> true
+ * instanceOf(Number, 1) //=> false
+ * ```
+ */
+function instanceOf(a: any, b: any): boolean
+function instanceOf(a: any, b?: any): boolean | ((b: any) => boolean) {
+  if (typeof b !== 'undefined') {
+    return b instanceof a
+  }
+
+  return b => instanceOf(a, b)
+}
+
+export default instanceOf

src/isNil.ts

@@ -0,0 +1,14 @@
+/**
+ * Test if a value is `null` or `undefined`
+ * ```js
+ * isEmpty(null) //=> true
+ * isEmpty(undefined) //=> true
+ * isEmpty(0) //=> false
+ * isEmpty(false) //=> false
+ * isEmpty(1) //=> false
+ * ```
+ */
+const isEmpty = (operand: any): boolean =>
+  operand === null || operand === undefined
+
+export default isEmpty

src/join.ts

@@ -0,0 +1,35 @@
+/**
+ * Test if the the second argument is an instance of the first argument. (curried)
+ * ```js
+ * instanceOf(Number)(new Number(1)) //=> true
+ * instanceOf(Number)(1) //=> false
+ * ```
+ */
+function join(list: Array<number | string>): (seperator: string) => string
+/**
+ * Test if the the second argument is an instance of the first argument.
+ * ```js
+ * instanceOf(Number, new Number(1)) //=> true
+ * instanceOf(Number, 1) //=> false
+ * ```
+ */
+function join(list: Array<number | string>, seperator: string): string
+function join(
+  list: Array<number | string>,
+  seperator?: string
+): string | ((seperator: string) => string) {
+  if (typeof seperator !== undefined) {
+    let result = ''
+
+    // eslint-disable-next-line unicorn/no-for-loop, @typescript-eslint/prefer-for-of
+    for (let i = 0; i < list.length; i++) {
+      result += `${list[i]}${seperator as string}`
+    }
+
+    return result.slice(0, -1)
+  }
+
+  return seperator => join(list, seperator)
+}
+
+export default join