From c742bff554722182553658c6eb18caed1e85ddeb Mon Sep 17 00:00:00 2001
From: Nathan Simpson <hello@nathansimpson.design>
Date: Wed, 18 Oct 2023 16:36:10 +1100
Subject: [PATCH] WIP

---
 .prettierrc   |  1 +
 index.js      | 26 ++++++++++++++++++++++----
 index.test.js | 38 ++++++++++++++++----------------------
 readme.md     | 24 +++++++++---------------
 4 files changed, 48 insertions(+), 41 deletions(-)
 create mode 100644 .prettierrc

diff --git a/.prettierrc b/.prettierrc
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/.prettierrc
@@ -0,0 +1 @@
+{}
diff --git a/index.js b/index.js
index 4e823d3..d2034f8 100644
--- a/index.js
+++ b/index.js
@@ -1,16 +1,34 @@
 const { hexToRGB, formatRGB, formatRGBA } = require("./utils");
 
 /**
+ * hexAlpha allows you to set an opacity value to a HEX color. It returns a string in the format of RGBA.
  * @param {string} input - A color in hexadecimal syntax. e.g. #fa6d01
  * @param {number} alpha - The desired opacity, from 0 to 1.
  * @returns {string} - The new color in rgba() or rgb() syntax.
  */
 const hexAlpha = (input, alpha) => {
-  const newColor = hexToRGB(input);
+  // ensure input is a valid hex color
+  if (typeof input !== "string" || !/^#([0-9A-Fa-f]{3}){1,2}$/.test(input)) {
+    throw new Error(
+      "Invalid input: input must be a valid hexadecimal color code. e.g. #fa6d01."
+    );
+  }
 
-  return typeof alpha === "number" && alpha >= 0 && alpha <= 1
-    ? formatRGBA(newColor, alpha)
-    : formatRGB(newColor);
+  // convert hex string to rgb map
+  const rgb = hexToRGB(input);
+
+  // if alpha is not provided, return rgb string
+  if (alpha === undefined) return formatRGB(rgb);
+
+  // ensure alpha is a valid number between 0 and 1
+  if (typeof alpha !== "number" || alpha < 0 || alpha > 1) {
+    throw new Error(
+      "Invalid alpha value: alpha must be a number between 0 and 1."
+    );
+  }
+
+  // return rgba string
+  return formatRGBA(rgb, alpha);
 };
 
 module.exports = hexAlpha;
diff --git a/index.test.js b/index.test.js
index 695d6e6..27b1c5f 100644
--- a/index.test.js
+++ b/index.test.js
@@ -1,33 +1,27 @@
 const hexAlpha = require("./index");
 
-test("#FFFFFF converts to rgb(255,255,255)", () => {
-  expect(hexAlpha("#ffffff")).toBe("rgb(255,255,255)");
-});
-
-test("#000000 converts to rgba(0,0,0,1)", () => {
+test("hexAlpha returns an RGBA value for a colour with an opacity", () => {
   expect(hexAlpha("#000000", 1)).toBe("rgba(0,0,0,1)");
-});
-
-test("#fa6d01 converts to rgb(250,109,1)", () => {
-  expect(hexAlpha("#fa6d01")).toBe("rgb(250,109,1)");
-});
-
-test("#f00 converts to rgba(0,0,0,1)", () => {
   expect(hexAlpha("#f00", 0.1)).toBe("rgba(255,0,0,0.1)");
+  expect(hexAlpha("#fa6d01", 0)).toBe("rgba(250,109,1,0)");
+  expect(hexAlpha("#fa6d01", 0.5)).toBe("rgba(250,109,1,0.5)");
 });
 
-test("HEX color and alpha converts to RGBA", () => {
-  expect(hexAlpha("#fa6d01", 0.1)).toBe("rgba(250,109,1,0.1)");
+test("hexAlpha returns an RGB value for a colour without an opacity", () => {
+  expect(hexAlpha("#ffffff")).toBe("rgb(255,255,255)");
+  expect(hexAlpha("#fa6d01")).toBe("rgb(250,109,1)");
 });
 
-test("HEX color with 0 or 1 alpha converts to RGBA", () => {
-  expect(hexAlpha("#fa6d01", 0)).toBe("rgba(250,109,1,0)");
-  expect(hexAlpha("#fa6d01", 1)).toBe("rgba(250,109,1,1)");
+test("hexAlpha throws an error for a colour with an invalid opacity", () => {
+  expect(hexAlpha("#fa6d01", "")).toThrowError();
+  expect(hexAlpha("#fa6d01", false)).toThrowError();
+  expect(hexAlpha("#fa6d01", -1)).toThrowError();
+  expect(hexAlpha("#fa6d01", 2.4)).toThrowError();
 });
 
-test("HEX color with invalid `alpha` converts to RGB", () => {
-  expect(hexAlpha("#fa6d01", "")).toBe("rgb(250,109,1)");
-  expect(hexAlpha("#fa6d01", false)).toBe("rgb(250,109,1)");
-  expect(hexAlpha("#fa6d01", -1)).toBe("rgb(250,109,1)");
-  expect(hexAlpha("#fa6d01", 2.4)).toBe("rgb(250,109,1)");
+test("hexAlpha throws an error for an invalid colour", () => {
+  expect(hexAlpha("invalid")).toThrowError();
+  expect(hexAlpha("#ffgg00")).toThrowError();
+  expect(hexAlpha("#ff000")).toThrowError();
+  expect(hexAlpha("#ff00000")).toThrowError();
 });
diff --git a/readme.md b/readme.md
index 5591f86..68e1f9c 100644
--- a/readme.md
+++ b/readme.md
@@ -1,20 +1,6 @@
 # HEX-ALPHA
 
-A really simple package that enables you to specify an opacity for your HEX colours.
-
-```
-HEX + Alpha = RGBA
-```
-
-## Installation
-
-```
-npm install hex-alpha
-// or
-yarn add hex-alpha
-```
-
-## Examples
+A simple function which allows you to set an opacity value to a HEX color. It returns a string in the format of RGBA.
 
 ```javascript
 import hexAlpha from "hex-alpha";
@@ -29,6 +15,14 @@ hexAlpha("#f00");
 // returns "rgb(255,0,0)"
 ```
 
+## Installation
+
+```
+npm install hex-alpha
+// or
+yarn add hex-alpha
+```
+
 ## Meetup talk
 
 I gave a talk about making HEX-Alpha at the Sydney Javascript meetup - SydJS. [Check it out here](https://www.youtube.com/watch?v=OQbF8Mx4iso).