fix Color.toString() issues: add 'hex' alias and correct 'hsla%' output

Author: Anshumancanrock

src/color/p5.Color.js

@@ -374,6 +374,7 @@ p5.Color = class Color {
    * @param {String} [format] how the color string will be formatted.
    * Leaving this empty formats the string as rgba(r, g, b, a).
    * '#rgb' '#rgba' '#rrggbb' and '#rrggbbaa' format as hexadecimal color codes.
+   * 'hex' is an alias for '#rrggbb'.
    * 'rgb' 'hsb' and 'hsl' return the color formatted in the specified color mode.
    * 'rgba' 'hsba' and 'hsla' are the same as above but with alpha channels.
    * 'rgb%' 'hsb%' 'hsl%' 'rgba%' 'hsba%' and 'hsla%' format as percentages.
@@ -408,6 +409,7 @@ p5.Color = class Color {
     const alpha = f[3]; // String representation uses normalized alpha
 
     switch (format) {
+      case 'hex':
       case '#rrggbb':
         return '#'.concat(
           a[0] < 16 ? '0'.concat(a[0].toString(16)) : a[0].toString(16),
@@ -552,7 +554,7 @@ p5.Color = class Color {
 
       case 'hsla%':
         if (!this.hsla) this.hsla = color_conversion._rgbaToHSLA(this._array);
-        return 'hsl('.concat(
+        return 'hsla('.concat(
           (100 * this.hsla[0]).toPrecision(3),
           '%, ',
           (100 * this.hsla[1]).toPrecision(3),

test/unit/color/p5.Color.js

@@ -996,5 +996,26 @@ suite('p5.Color', function() {
     test('should not mutate color levels', function() {
       assert.deepEqual(c.levels, [128, 0, 128, 128]);
     });
+
+    test('should format as #rrggbb hex string', function() {
+      var testColor = myp5.color(153, 50, 204); // darkorchid
+      assert.equal(testColor.toString('#rrggbb'), '#9932cc');
+    });
+
+    test('should format as hex string with "hex" alias', function() {
+      var testColor = myp5.color(153, 50, 204); // darkorchid
+      assert.equal(testColor.toString('hex'), '#9932cc');
+    });
+
+    test('should format hsla% with correct function name', function() {
+      var testColor = myp5.color(128, 0, 128, 128);
+      var result = testColor.toString('hsla%');
+      assert.include(result, 'hsla(');
+    });
+
+    test('should handle single digit hex values with padding', function() {
+      var testColor = myp5.color(10, 5, 15);
+      assert.equal(testColor.toString('#rrggbb'), '#0a050f');
+    });
   });
 });