util: colorize text with hex colors

Author: araujogui

lib/util.js

@@ -112,6 +112,55 @@ function escapeStyleCode(code) {
   return `\u001b[${code}m`;
 }
 
+/**
+ * @param {number} code
+ * @returns {number}
+ */
+function hexToNibble(code) {
+  // '0'-'9'
+  if (code >= 48 && code <= 57) return code - 48;
+  // 'A'-'F'
+  if (code >= 65 && code <= 70) return code - 55;
+  // 'a'-'f'
+  if (code >= 97 && code <= 102) return code - 87;
+  return -1;
+}
+
+const hastagCharcode = 35
+
+/**
+ * Parses a hex color in #RGB or #RRGGBB form.
+ * Returns RGB bytes on success, otherwise undefined
+ * .
+ * @param {string} format
+ * @returns {[number, number, number] | undefined}
+ */
+function parseHexColor(format) {
+  if (format.length !== 4 && format.length !== 7) return;
+
+  if (format.length === 4) {
+    const r = hexToNibble(format.charCodeAt(1));
+    const g = hexToNibble(format.charCodeAt(2));
+    const b = hexToNibble(format.charCodeAt(3));
+
+    if ((r | g | b) < 0) return;
+
+    // Duplicate nibbles: #RGB -> #RRGGBB
+    return [(r << 4) | r, (g << 4) | g, (b << 4) | b];
+  }
+
+  const r1 = hexToNibble(format.charCodeAt(1));
+  const r2 = hexToNibble(format.charCodeAt(2));
+  const g1 = hexToNibble(format.charCodeAt(3));
+  const g2 = hexToNibble(format.charCodeAt(4));
+  const b1 = hexToNibble(format.charCodeAt(5));
+  const b2 = hexToNibble(format.charCodeAt(6));
+
+  if ((r1 | r2 | g1 | g2 | b1 | b2) < 0) return;
+
+  return [(r1 << 4) | r2, (g1 << 4) | g2, (b1 << 4) | b2];
+}
+
 /**
  * @param {string | string[]} format
  * @param {string} text
@@ -144,6 +193,15 @@ function styleText(format, text, { validateStream = true, stream = process.stdou
   const codes = [];
   for (const key of formatArray) {
     if (key === 'none') continue;
+
+    if (typeof key === 'string' && key.charCodeAt(0) === hastagCharcode) {
+      const rgb = parseHexColor(key);
+      if (rgb !== undefined && !skipColorize) {
+        ArrayPrototypePush(codes, [`38;2;${rgb[0]};${rgb[1]};${rgb[2]}`, 39]);
+      }
+      continue;
+    }
+
     const formatCodes = inspect.colors[key];
     // If the format is not a valid style, throw an error
     if (formatCodes == null) {

test/parallel/test-util-styletext.js

@@ -36,6 +36,37 @@ assert.throws(() => {
   code: 'ERR_INVALID_ARG_VALUE',
 });
 
+assert.strictEqual(
+  util.styleText('#fff', 'test', { validateStream: false }),
+  '\u001b[38;2;255;255;255mtest\u001b[39m',
+);
+
+assert.strictEqual(
+  util.styleText('#ffcc00', 'test', { validateStream: false }),
+  '\u001b[38;2;255;204;0mtest\u001b[39m',
+);
+
+assert.strictEqual(
+  util.styleText(['#ffcc00', 'bold'], 'test', { validateStream: false }),
+  '\x1B[38;2;255;204;0m\x1B[1mtest\x1B[22m\x1B[39m',
+);
+
+
+['#ff', '#zzzzzz', '#12345g'].forEach((invalidHex) => {
+  assert.doesNotThrow(() => {
+    util.styleText(invalidHex, 'test', { validateStream: false });
+  });
+  assert.strictEqual(
+    util.styleText(invalidHex, 'test', { validateStream: false }),
+    noChange,
+  );
+});
+
+assert.strictEqual(
+  util.styleText(['red', '#zzzzzz'], 'test', { validateStream: false }),
+  styled,
+);
+
 assert.strictEqual(
   util.styleText('red', 'test', { validateStream: false }),
   '\u001b[31mtest\u001b[39m',
@@ -183,6 +214,14 @@ if (fd !== -1) {
       const output = util.styleText(['red'], 'test', { stream: writeStream });
       assert.strictEqual(output, testCase.expected);
     }
+
+    // When colors are disabled, hex colors should also be disabled.
+    if (testCase.expected === noChange) {
+      const output = util.styleText('#ffcc00', 'test', { stream: writeStream });
+      assert.strictEqual(output, noChange);
+      const outputArray = util.styleText(['#ffcc00'], 'test', { stream: writeStream });
+      assert.strictEqual(outputArray, noChange);
+    }
     process.env = originalEnv;
   });
 } else {