Relevant links:

• Live WebVTT Validator.
• WebVTT Specification

You can load the parser.js file into your HTML page and the API will become available on window. Alternatively you can install it using bower (webvtt) or npm (npm install webvtt-parser).

This module exports classes to either through window or require()/import; the ones you are likely to need are WebVTTParser and WebVTTSerializer.

To parse a WebVTT string:

import { WebVTTParser } from 'webvtt-parser';
const parser = new WebVTTParser();
const tree = parser.parse(someVTT, 'metadata');

By default, the WebVTT parser only recognizes a small subset of named character entities. If you want the full spec-compliant behavior, pass the content of [[html-entities.json]] to the WebVTTParser() constructor.

To serialize a WebVTT tree to string:

import { WebVTTSerializer } from 'webvtt-parser';
const seri = new WebVTTSerializer();
const tree = seri.serialize(vttTree.cues)