Fixes an issue with Google Chrome Speech Synthesis where long texts pause mid-speaking. The function takes in a speechUtterance object and intelligently chunks it into smaller blocks of text that are stringed together one after the other. Basically, you can play any length of text. See http://stackoverflow.com/questions/21947730/chrome-speech-sy…

chunkify.js

/**
 * Chunkify
 * Google Chrome Speech Synthesis Chunking Pattern
 * Fixes inconsistencies with speaking long texts in speechUtterance objects 
 * Licensed under the MIT License
 *
 * Peter Woolley and Brett Zamir
 */
 
var speechUtteranceChunker = function (utt, settings, callback) {
    settings = settings || {};
    var newUtt;
    var txt = (settings && settings.offset !== undefined ? utt.text.substring(settings.offset) : utt.text);
    if (utt.voice && utt.voice.voiceURI === 'native') { // Not part of the spec
        newUtt = utt;
        newUtt.text = txt;
        newUtt.addEventListener('end', function () {
            if (speechUtteranceChunker.cancel) {
                speechUtteranceChunker.cancel = false;
            }
            if (callback !== undefined) {
                callback();
            }
        });
    }
    else {
        var chunkLength = (settings && settings.chunkLength) || 160;
        var pattRegex = new RegExp('^[\\s\\S]{' + Math.floor(chunkLength / 2) + ',' + chunkLength + '}[.!?,]{1}|^[\\s\\S]{1,' + chunkLength + '}$|^[\\s\\S]{1,' + chunkLength + '} ');
        var chunkArr = txt.match(pattRegex);
 
        if (chunkArr[0] === undefined || chunkArr[0].length <= 2) {
            //call once all text has been spoken...
            if (callback !== undefined) {
                callback();
            }
            return;
        }
        var chunk = chunkArr[0];
        newUtt = new SpeechSynthesisUtterance(chunk);
        var x;
        for (x in utt) {
            if (utt.hasOwnProperty(x) && x !== 'text') {
                newUtt[x] = utt[x];
            }
        }
        newUtt.addEventListener('end', function () {
            if (speechUtteranceChunker.cancel) {
                speechUtteranceChunker.cancel = false;
                return;
            }
            settings.offset = settings.offset || 0;
            settings.offset += chunk.length - 1;
            speechUtteranceChunker(utt, settings, callback);
        });
    }
 
    if (settings.modifier) {
        settings.modifier(newUtt);
    }
    console.log(newUtt); //IMPORTANT!! Do not remove: Logging the object out fixes some onend firing issues.
    //placing the speak invocation inside a callback fixes ordering and onend issues.
    setTimeout(function () {
        speechSynthesis.speak(newUtt);
    }, 0);
};

Thanks, nice helpful script but I found 2 issues (on chrome 56):

• It was reading "DOT" as the start of the second sentence.
• End event wasn't firing due to "...cannot read [0] of null.." error.

This has been fixed here: https://gist.github.com/hsed/ef4a2d17f76983588cb6d2a11d4566d6.

I modified it to use my selected voice which wasn't working by adding newUtt.voice = utt.voice; after initializing the newUtt from the chunk.

However, this caused timing issues. I have pauses in between chunks. It sounds un-natural.

Hello author! I'm putting an argument based on my fresh experience with speechSynthesis. I'm trying to understand your code but most of the things are not giving sense to me. I want to use this code to make my following code speak the given text up to the end. Can you guide me on how to do this?

const read = () => {
            const textArea = document.getElementById("textarea");
            const btn = document.getElementById("btn");
            const input = textArea.value;
            const msg = new SpeechSynthesisUtterance(input);
            window.speechSynthesis.speak(msg);
        }
const cancel = () => {
            window.speechSynthesis.cancel();
        }

THANKS IN ADVANCE!

This works perfectly on mobile as well, but how can i have control over resume and cancel methods? like on click the content is reading but i want some additional functionality also. I have created some states and based on that it should read my content. Like, isArticle = "playing" || "paused" || "resumed" || "canceled". playing will speak. paused will pause and canceled with stop.