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Helpers and YouTubeApi are static utility classes used throughout the simulator codebase. Neither class holds instance state — every method is static, so you call them directly on the class name without constructing an object. Helpers lives in js/helpers/helpers.js and provides general-purpose browser and string utilities. YouTubeApi lives in js/helpers/youtube-ctrl.js and wraps the YouTube IFrame API player methods used by channel implementations.
All methods on both Helpers and YouTubeApi are static. You never call new Helpers() or new YouTubeApi() — always call Helpers.methodName() or YouTubeApi.methodName() directly.

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Helpers

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Helpers.isMobile()

Helpers.isMobile(): object
Returns a plain object with per-platform detection functions. Each function tests navigator.userAgent with a regular expression and returns the regex match result (truthy on a match, null otherwise). 
Helpers.isMobile().Android()     // matches /Android/i
Helpers.isMobile().BlackBerry()  // matches /BlackBerry/i
Helpers.isMobile().iOS()         // matches /iPhone|iPad|iPod/i
Helpers.isMobile().Opera()       // matches /Opera Mini/i
Helpers.isMobile().Windows()     // matches /IEMobile/i
Helpers.isMobile().any()         // truthy if any of the above match
The simulator uses isMobile().any() in TV.startUp() to conditionally add the .scanlines overlay and register the resize handler — both are skipped on mobile: 
if (!Helpers.isMobile().any()) {
    $(window).resize(() => { this.handleResize(); });
    $('.screen').addClass('scanlines');
}

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Helpers.padLeft(nr, n, str?)

Helpers.padLeft(nr: number | string, n: number, str?: string): string
Left-pads nr to at least n characters using the pad character str. If the string representation of nr is already n characters or longer, it is returned unchanged.
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nr
number | string
required
The value to pad.
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n
number
required
The minimum desired output length.
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str
string
default:"'0'"
The pad character. Defaults to '0' when omitted or undefined.
Examples: 
Helpers.padLeft(5, 3)     // → '005'
Helpers.padLeft(12, 2)    // → '12'
Helpers.padLeft(7, 3, ' ')// → '  7'
The simulator uses padLeft in two places:
  • TV.showChannel builds the layout path: channels/${Helpers.padLeft(number, 3)}/layout.html
  • TV.showChannel sets the channel-number overlay: Helpers.padLeft(number, 2)

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Helpers.loadScript(scriptUrl)

Helpers.loadScript(scriptUrl: string): Promise<void>
Dynamically injects a <script> element into <head> and returns a Promise that resolves when the script fires its onload event, or rejects on error.
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scriptUrl
string
required
The fully-qualified URL of the script to load.
// Inject an external script and wait for it to be ready
await Helpers.loadScript('https://www.youtube.com/iframe_api');
YouTubeApi.loadYouTubeAPI() calls this method internally. You can also use it directly when a channel needs to load a third-party library before its show() logic runs.
The onerror handler in the source contains a bug: reject(Error('Error loading ' + globalName || scriptUrl)) references globalName, which is not defined in scope. Due to JavaScript operator precedence this evaluates as reject(Error('Error loading ' + undefined) || scriptUrl), so the rejection message will read 'Error loading undefined' rather than the script URL. The onload path is unaffected.

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YouTubeApi

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YouTubeApi.loadYouTubeAPI()

static async YouTubeApi.loadYouTubeAPI(): Promise<void>
Injects the YouTube IFrame API script by calling Helpers.loadScript("https://www.youtube.com/iframe_api"). Called by TV.startUp() during initialization. When the script loads, the global onYouTubeIframeAPIReady callback fires automatically.

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YouTubeApi.restartVideo(player)

static YouTubeApi.restartVideo(player: YT.Player): void
Stops the player and immediately resumes playback by calling stopVideo then playVideo on the player instance.
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player
YT.Player
required
An initialized YouTube IFrame API player object.

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YouTubeApi.stopVideo(player)

static YouTubeApi.stopVideo(player: YT.Player): void
Stops playback by calling player.stopVideo(). Called by Channel.teardown() if this.player is set, ensuring the video stops when switching channels.
​
player
YT.Player
required
An initialized YouTube IFrame API player object.

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YouTubeApi.toggleMuteVideo(player)

static YouTubeApi.toggleMuteVideo(player: YT.Player): boolean
Toggles the mute state of the player. If currently muted, calls player.unMute(); otherwise calls player.mute(). Returns true if the player is now muted after the toggle, false if it is now unmuted.
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player
YT.Player
required
An initialized YouTube IFrame API player object.
// In TV.toggleMute():
this.muted = YouTubeApi.toggleMuteVideo(this.channel.player);
The return value is !player.isMuted() evaluated after the toggle call. Because the YouTube IFrame API’s isMuted() can have a brief async lag, always use this.muted (stored in the TV instance) as the canonical mute state rather than querying the player directly.

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YouTubeApi.muteVideo(player)

static YouTubeApi.muteVideo(player: YT.Player): void
Unconditionally mutes the player by calling player.mute().
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player
YT.Player
required
An initialized YouTube IFrame API player object.

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YouTubeApi.unmuteVideo(player)

static YouTubeApi.unmuteVideo(player: YT.Player): void
Unconditionally unmutes the player by calling player.unMute().
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player
YT.Player
required
An initialized YouTube IFrame API player object.

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Global Callback

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onYouTubeIframeAPIReady()

function onYouTubeIframeAPIReady(): void
A globally scoped function required by the YouTube IFrame API. When the IFrame API script finishes loading, YouTube’s infrastructure calls this function automatically. The simulator’s implementation dispatches a custom DOM event: 
function onYouTubeIframeAPIReady() {
    document.dispatchEvent(new CustomEvent('youtubeReady', {}));
}
TV.startUp() listens for the youtubeReady event via document.addEventListener('youtubeReady', ...) and uses it as the signal to fetch data/guide.xml and load the default channel. This decouples the guide data fetch from the script-load callback, keeping the TV class independent of the global function name.

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