Speech synthesis for a string by character.

speech.js

class SpeechGenerator {
	constructor() {
		this._word_pause = 8;
		this._char_pause = 8;
		this._ready = false;
		this._queued = [];
		this._voice_index = 0;
		this._rate = 1;
		var my = this;
		window.speechSynthesis.addEventListener('voiceschanged', function() {
			my._voice = window.speechSynthesis.getVoices()[my._voice_index];
			my._ready = true;
			for (let str of my._queued) {
				my.keyString(str);
			}
		});
	}
	get voice() {
		return this._voice;
	}
	keyString(str) {
		if (!this._ready) {
			this._queued.push(str);
			return;
		}
		var speech = "";
		for (let c of str) {
			if (c == " ") {
				for (let i=0;i<=this._word_pause;i++) speech += "... ";
			} else {
				speech += c.toUpperCase();
				for (let i=0;i<=this._char_pause;i++) speech += '... ';
			}
		}
		var msg = new SpeechSynthesisUtterance(speech);
		msg.voice = this.voice;
		msg.rate = this._rate;
		window.speechSynthesis.speak(msg);
	}
}