Add TTS for node-addon-api (#871)

scripts/node-addon-api/lib/non-streaming-tts.js

@@ -0,0 +1,25 @@
+const addon = require('./addon.js');
+
+class OfflineTts {
+  constructor(config) {
+    this.handle = addon.createOfflineTts(config);
+    this.config = config;
+
+    this.numSpeakers = addon.getOfflineTtsNumSpeakers(this.handle);
+    this.sampleRate = addon.getOfflineTtsSampleRate(this.handle);
+  }
+
+  /*
+   input obj: {text: "xxxx", sid: 0, speed: 1.0}
+   where text is a string, sid is a int32, speed is a float
+
+   return an object {samples: Float32Array, sampleRate: <a number>}
+   */
+  generate(obj) {
+    return addon.offlineTtsGenerate(this.handle, obj);
+  }
+}
+
+module.exports = {
+  OfflineTts,
+}