This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
The charIndex read-only property of the SpeechSynthesisUtterance interface returns the index position of the character in the SpeechSynthesisUtterance.text that was being spoken when the event was triggered.
Syntax
event.charIndex;
Value
A number.
Examples
utterThis.onpause = function(event) {
  var char = event.utterance.text.charAt(event.charIndex);
  console.log('Speech paused at character ' + event.charIndex + ' of "' +
  event.utterance.text + '", which is "' + char + '".');
}
Specifications
| Specification | Status | Comment | 
|---|---|---|
| Web Speech API The definition of 'charIndex' in that specification. | Draft | 
Browser compatibility
| Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) | 
|---|---|---|---|---|---|---|
| Basic support | 33 | (Yes) | 49 (49) | No support | ? | 7 | 
| Feature | Android | Chrome | Edge | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile | 
|---|---|---|---|---|---|---|---|---|
| Basic support | (Yes) | (Yes) | (Yes) | No support | 2.0 | No support | No support | 7.1 |