Expand keyIsDown() to work with characters as arguments

src/events/keyboard.js

@@ -807,11 +807,12 @@ p5.prototype._onblur = function(e) {
  *
  * `keyIsDown()` can check for key presses using
  * <a href="#/p5/keyCode">keyCode</a> values, as in `keyIsDown(37)` or
- * `keyIsDown(LEFT_ARROW)`. Key codes can be found on websites such as
+ * `keyIsDown(LEFT_ARROW)` or an alphanumeric string value `keyIsDown('A')` or `keyIsDown('a')`
+ * Key codes can be found on websites such as
  * <a href="https://keycode.info" target="_blank">keycode.info</a>.
  *
  * @method keyIsDown
- * @param {Number}          code key to check.
+ * @param {Number|String}         code key to check.
  * @return {Boolean}        whether the key is down or not.
  *
  * @example
@@ -872,6 +873,50 @@ p5.prototype._onblur = function(e) {
  *   background(200);
  *
  *   describe(
+ *     'A gray square with a black circle at its center. The circle moves when the user presses "W", "A", "S", or "D". It leaves a trail as it moves.'
+ *   );
+ * }
+ *
+ * function draw() {
+ *   // Update x and y if "W", "A", "S", or "D" is pressed.
+ *   if (keyIsDown('A') === true) {
+ *     x -= 1;
+ *   }
+ *
+ *   if (keyIsDown('D') === true) {
+ *     x += 1;
+ *   }
+ *
+ *   if (keyIsDown('W') === true) {
+ *     y -= 1;
+ *   }
+ *
+ *   if (keyIsDown('S') === true) {
+ *     y += 1;
+ *   }
+ *
+ *   // Style the circle.
+ *   fill(0);
+ *
+ *   // Draw the circle.
+ *   circle(x, y, 5);
+ * }
+ * </code>
+ * </div>
+ *
+ * <div>
+ * <code>
+ * // Click on the canvas to begin detecting key presses.
+ *
+ * let x = 50;
+ * let y = 50;
+ *
+ * function setup() {
+ *   createCanvas(100, 100);
+ *
+ *   background(200);
+ *
+ *   describe(
  *     'A gray square with a black circle at its center. The circle moves when the user presses an arrow key. It leaves a trail as it moves.'
  *   );
  * }
@@ -905,6 +950,9 @@ p5.prototype._onblur = function(e) {
  */
 p5.prototype.keyIsDown = function(code) {
   p5._validateParameters('keyIsDown', arguments);
+  if (typeof code === 'string' && code.length === 1) {
+    code = code.toUpperCase().charCodeAt(0);
+  }
   return this._downKeys[code] || false;
 };
 

test/unit/events/keyboard.js

@@ -191,5 +191,9 @@ suite('Keyboard Events', function() {
     test('keyIsDown should return false if key is not down', function() {
       assert.strictEqual(myp5.keyIsDown(35), false);
     });
+
+    test('keyIsDown should return false if key has length more than 1', function() {
+      assert.strictEqual(myp5.keyIsDown('ab'), false);
+    });
   });
 });