Init commit with many years of arduino sketches and projects. I dont know if the esp8266 includes much, but there are also libraries. I hope they dont have crazy automatic versioning through the Arduino IDE.

Projects/ProgLab/toneAC.h/toneAC.h.ino

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+// ---------------------------------------------------------------------------
+// Connect your piezo buzzer (without internal oscillator) or speaker to these pins:
+//   Pins  9 & 10 - ATmega328, ATmega128, ATmega640, ATmega8, Uno, Leonardo, etc.
+//   Pins 11 & 12 - ATmega2560/2561, ATmega1280/1281, Mega
+//   Pins 12 & 13 - ATmega1284P, ATmega644
+//   Pins 14 & 15 - Teensy 2.0
+//   Pins 25 & 26 - Teensy++ 2.0
+// Be sure to include an inline 100 ohm resistor on one pin as you normally do when connecting a piezo or speaker.
+// ---------------------------------------------------------------------------
+
+#include "toneAC.h"
+
+// Melody liberated from the toneMelody Arduino example sketch by Tom Igoe.
+int melody[] = { 262, 196, 196, 220, 196, 0, 247, 262 };
+int noteDurations[] = { 4, 8, 8, 4, 4, 4, 4, 4 };
+
+void setup() {} // Nothing to setup, just start playing!
+
+void loop() {
+  for (unsigned long freq = 125; freq <= 15000; freq += 10) {  
+    toneAC(freq); // Play the frequency (125 Hz to 15 kHz sweep in 10 Hz steps).
+    delay(1);     // Wait 1 ms so you can hear it.
+  }
+  toneAC(); // Turn off toneAC, can also use noToneAC().
+
+  delay(1000); // Wait a second.
+
+  for (int thisNote = 0; thisNote < 8; thisNote++) {
+    int noteDuration = 1000/noteDurations[thisNote];
+    toneAC(melody[thisNote], 10, noteDuration, true); // Play thisNote at full volume for noteDuration in the background.
+    delay(noteDuration * 4 / 3); // Wait while the tone plays in the background, plus another 33% delay between notes.
+  }
+
+  while(1); // Stop (so it doesn't repeat forever driving you crazy--you're welcome).
+}