DIAGRAM.md

Flow chart of the counter

Initialization

The code is run automatically when the script is parsed. This step defines common code used by all counters on the page.

flowchart TB
    subgraph GlobalStorage
      GS[Creates an empty storage and fills in some basic info. <br>The global storage is shared by all counter on a page. <br>It contains common data and allows intercounter communication, <br>e.g. register semaphores for actions that should be performed once for all counters.]
    end

    subgraph Mappings
      direction LR

      subgraph MD[Create mappings that define which sender/middleware/transport combination to use with each provider.]
      end

      subgraph ProviderMaps
        direction LR

        ProviderMap --> Sender
        ProviderMap --> ProviderMiddlewares
        ProviderMap --> Transports
      end

      subgraph SenderMaps
        direction LR
        
        SenderMap --> SenderMiddlewares
      end
    end

    subgraph CounterConstructor
      CC[The constructor function that starts a counter]
    end

    subgraph StaticMethods
      SM[Static counter methods not ties to a particular counter instance]
    end

    subgraph StackProxy
      SP[A handler of events from the proxy stack]
    end

    GlobalStorage --> Mappings
    Mappings --> CounterConstructor
    CounterConstructor --> StaticMethods
    StaticMethods --> StackProxy

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Constructor

The code run is triggered by a user: either calling the constructor (new Ya.Metrika2(XXXXXX)) or via proxy stack (ym(XXXXXX, "init", {});).

flowchart TB
  ParseOptions

  subgraph PrioritizedProviders
    PP[Anything that needs to be done <br>before the start and requires counter options.]
  end

  subgraph DebugConsole
  end

  subgraph BeforeHitProviders
    BHP[Sets info required before the first hit <br>or runs providers that need to track the first hit.]
  end

  subgraph Hit
    H[The first hit - pageview. Sent is ASAP. <br>The response comprises counter settings <br>which are saved for use by other providers.]
  end

  subgraph SynchronousProviders
    SP[The stuff that is not dependent on counter settings <br>and required to be run ASAP.]
  end

  subgraph CounterMethodsInitialization
    CMI[All the methods provided via JS API are registered on the counter instance.]
  end

  subgraph AsynchronousProviders
    ASP[The stuff that is dependent on counter settings <br>or is not essentially necessary to be run ASAP.]
  end

  ParseOptions --> PrioritizedProviders
  PrioritizedProviders --> DebugConsole
  DebugConsole --> BeforeHitProviders
  BeforeHitProviders --> Hit
  Hit --> SynchronousProviders
  SynchronousProviders --> CounterMethodsInitialization
  CounterMethodsInitialization --> AsynchronousProviders

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Request flow

Any request provider performs some initial actions:

• gathers data from page and browser;
• subscribes for user or DOM events;
• prepares data for further processing by a sender/middlewares.

Then a sender is called.

flowchart TB
  subgraph Provider
    P[Gathers some basic info or subscribes for future events.<br>Performs event data parsing and triggers a sender.]
  end

  subgraph Sender
    S[Sets basic request info, defines backend endpoint and the most common parameters.]
  end

  subgraph Middlewares
    M[Append the request data with any useful info.]
  end

  subgraph Transport
    T[Iterate through a set of transports until the request is successfully sent to the backend.]
  end

  Provider --> Sender
  Sender --> Middlewares
  Middlewares --> Transport

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