bilibili/flv.js · error · InvalidArgumentException

MediaDataSource must be an javascript object!

Error message

MediaDataSource must be an javascript object!

What it means

createPlayer(mediaDataSource, optionalConfig) validates that mediaDataSource is a non-null JavaScript object before inspecting it. Passing null, undefined, a string, or a number cannot yield a usable player configuration, so an InvalidArgumentException is thrown immediately. It is a fail-fast input validation error.

Source

Thrown at src/flv.js:39

import {BaseLoader, LoaderStatus, LoaderErrors} from './io/loader.js';
import FlvPlayer from './player/flv-player.js';
import NativePlayer from './player/native-player.js';
import PlayerEvents from './player/player-events.js';
import {ErrorTypes, ErrorDetails} from './player/player-errors.js';
import LoggingControl from './utils/logging-control.js';
import {InvalidArgumentException} from './utils/exception.js';

// here are all the interfaces

// install polyfills
Polyfill.install();


// factory method
function createPlayer(mediaDataSource, optionalConfig) {
    let mds = mediaDataSource;
    if (mds == null || typeof mds !== 'object') {
        throw new InvalidArgumentException('MediaDataSource must be an javascript object!');
    }

    if (!mds.hasOwnProperty('type')) {
        throw new InvalidArgumentException('MediaDataSource must has type field to indicate video file type!');
    }

    switch (mds.type) {
        case 'flv':
            return new FlvPlayer(mds, optionalConfig);
        default:
            return new NativePlayer(mds, optionalConfig);
    }
}


// feature detection
function isSupported() {
    return Features.supportMSEH264Playback();

View on GitHub (pinned to 42343088f2)

Solutions

1. Pass a proper object: createPlayer({type:'flv', isLive:true, url:'...'})
2. If the config loads asynchronously, only call createPlayer after it resolves (or in a ready/effect callback)
3. Log/inspect the value right before the call to confirm it is an object

Example fix

// before
createPlayer('https://example.com/video.flv', config); // throws
// after
createPlayer({type: 'flv', isLive: true, url: 'https://example.com/video.flv'}, config);

if (mediaDataSource == null || typeof mediaDataSource !== 'object') {
  throw new TypeError('mediaDataSource must be a non-null object');
}

function isMediaDataSource(v) {
  return typeof v === 'object' && v !== null && !Array.isArray(v) && typeof v.type === 'string';
}

try {
  const player = createPlayer(mediaDataSource, config);
} catch (e) {
  if (e.name === 'InvalidArgumentException') {
    console.error('Bad mediaDataSource, got:', typeof mediaDataSource, mediaDataSource);
  } else { throw e; }
}

When it happens

Trigger: Calling createPlayer(null), createPlayer(undefined), createPlayer('https://example.com/video.flv') (a URL string instead of an object), or the variable holding the config being unfilled due to a failed fetch/parse.

Common situations: Passing a plain URL string instead of {type:'flv', url:...}; async config not yet loaded when createPlayer runs; JSON.parse failure silently yielding null; typos assigning the config to a different variable.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• MediaDataSource must has type field to indicate video file t
• NativePlayer(${mediaDataSource.type}) doesn't support multip

AI-assisted analysis of bilibili/flv.js@42343088f2 (2026-09-01). Data as JSON: /api/errors/70e1730a4eb7885d. Report an issue: GitHub.