(Web | Service) Worker import UMD script - How to check the context

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(Web | Service) Worker import UMD script - How to check the context

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#1 by (0 votes)

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How to check if the script is being called from a (Web | Service) Worker?

I have used UMD for a long time and I am migrating my projects to support SW ... although, I use many features available only on window objects and document many features (utilities) I want to share in SW (import) more I just have to "duplicate" these resources by separating them into new files to actually import ( importScripts() ) because it's the same thing I do when using Web Workers.

I started to look at this in a more "critical" way and ask myself:

How to identify in what context the code is running?

Based on this "context" export only a set of utilities ... per hour what I have is based on this:

;((root, factory) => {
    // UMD (Universal Module Definition) [improved]
    if ( typeof define === 'function' && define.amd ) {
        define(['exports'], factory)
    } else if ( typeof exports !== 'undefined' ) {
        factory(exports)
    } else {
        factory(root)
    }
})(this, exports => {    

    let A, B, C    

    const A = 'a'
    const B = 'b'
    const C = 'c'    

    function Plugin(){}
    // prototype
    Plugin.prototype.functionA = function(param) {}
    Plugin.prototype.functionB = function(param) {}
    Plugin.prototype.functionC = function(param) {}    

    exports.CorePlugin = new Plugin()
});

Exporting everything that is "exportable" to the object window :

window.CorePlugin

How could something like this:

function SWPlugin() {
    // um conjunto de ferramentas exclusivas para Service Worker
}

function WWPlugin() {
    // exportar um conjunto de ferramentas exclusivas para Web Worker
}

function Plugin() {
    // a exportação padrão para 'window'
}

// verificar
if ( ISWORKER ) {
    exports.CorePlugin = new WWPlugin()
} else if ( ISSERVICE ) {
    exports.CorePlugin = new SWPlugin()
} else {
    exports.CorePlugin = new Plugin()
}

javascript web-worker service-worker

asked by anonymous 16.03.2018 / 04:33

1 answer

Change type react-native-masked-text Binary file to buffer in c

score 0 · Answer 1

Using self I was able to get to the expected result

let IsServiceWorkerContext = ( ('WorkerGlobalScope' in self) && ('ServiceWorkerGlobalScope' in self) ) ? true : false,
    IsWebWorkerContext     = ( ('WorkerGlobalScope' in self) && !('ServiceWorkerGlobalScope' in self) ) ? true : false,
    IsWebBrowserContext    = ( ('window' in self && 'document' in self) && !IsServiceWorkerContext && !IsWebWorkerContext) ? true : false

The only change was to prevent the use of objects such as window , document , among others that are not available in Web Workers and Service Worker.

const noop = () => {}
const dc = IsWebBrowserContext ? document : false,
    wd = IsWebBrowserContext ? window : self,
    nv = wd.navigator,
    ua = nv.userAgent,
    ls = IsWebBrowserContext ? wd.localStorage : noop(),
    ss = IsWebBrowserContext ? wd.sessionStorage : noop(),
    XHR = IsWebBrowserContext ? ( new XMLHttpRequest() ) : noop(),
    FD  = ( new FormData() ),
    // global get APIS...
    indexedDB      = wd.indexedDB || false,
    IDBTransaction = wd.IDBTransaction || false,
    IDBKeyRange    = wd.IDBKeyRange || false,
    URL            = wd.URL || false,
    Geolocation    = IsWebBrowserContext ? nv.geolocation : noop(),
    RegLogout      = IsWebBrowserContext ? nv.sendBeacon : noop(),
    Notifics       = IsWebBrowserContext ? wd.Notification : noop(),
    Fetch          = wd.fetch || false,
    Storage        = IsWebBrowserContext ? wd.Storage : noop(),
    Worker         = IsWebBrowserContext ? wd.Worker : noop(),
    ServiceWorker  = IsWebBrowserContext ? nv.serviceWorker : noop(),
    Promise        = wd.Promise || false

Use logic (check the context) in some auto-executable functions and "prototype" functions and objects specific to the "context."

if ( IsServiceWorkerContext ) {
    Plugin.prototype.example1 = noop()
    Plugin.prototype.example2 = noop()
} else if ( IsWebWorkerContext ) {
    Plugin.prototype.example1 = noop()
    Plugin.prototype.example3 = noop()
} else if ( IsWebBrowserContext ) {
    Plugin.prototype.example4 = noop()
    Plugin.prototype.example5 = noop()
    //...
}
exports.CorePlugin = new Plugin()