events: rename high & low watermark for consistency

PR-URL: #52080
Fixes: #52078
Refs: #41276
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

lib/events.js

@@ -1051,8 +1051,8 @@ function eventTargetAgnosticAddListener(emitter, name, listener, flags) {
  * @param {{
  *    signal: AbortSignal;
  *    close?: string[];
- *    highWatermark?: number,
- *    lowWatermark?: number
+ *    highWaterMark?: number,
+ *    lowWaterMark?: number
  *   }} [options]
  * @returns {AsyncIterator}
  */
@@ -1062,10 +1062,12 @@ function on(emitter, event, options = kEmptyObject) {
   validateAbortSignal(signal, 'options.signal');
   if (signal?.aborted)
     throw new AbortError(undefined, { cause: signal?.reason });
-  const highWatermark = options.highWatermark ?? NumberMAX_SAFE_INTEGER;
-  validateInteger(highWatermark, 'options.highWatermark', 1);
-  const lowWatermark = options.lowWatermark ?? 1;
-  validateInteger(lowWatermark, 'options.lowWatermark', 1);
+  // Support both highWaterMark and highWatermark for backward compatibility
+  const highWatermark = options.highWaterMark ?? options.highWatermark ?? NumberMAX_SAFE_INTEGER;
+  validateInteger(highWatermark, 'options.highWaterMark', 1);
+  // Support both lowWaterMark and lowWatermark for backward compatibility
+  const lowWatermark = options.lowWaterMark ?? options.lowWatermark ?? 1;
+  validateInteger(lowWatermark, 'options.lowWaterMark', 1);
 
   // Preparing controlling queues and variables
   FixedQueue ??= require('internal/fixed_queue');

lib/internal/readline/interface.js

@@ -1359,7 +1359,7 @@ class Interface extends InterfaceConstructor {
       this[kLineObjectStream] = EventEmitter.on(
         this, 'line', {
           close: ['close'],
-          highWatermark: 1024,
+          highWaterMark: 1024,
           [kFirstEventParam]: true,
         });
     }