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VASTClient

The VASTClient class provides a client to manage the fetching and parsing of VAST documents.

Constructor

The constructor signature is:

constructor(cappingFreeLunch, cappingMinimumTimeInterval, customStorage)

All the parameters are optional.

Parameters

  • cappingFreeLunch: Number - Used to set the cappingFreeLunch property of the class, if not provided a default value of 0 is used for the property
  • cappingMinimumTimeInterval: Number - Used to set the cappingMinimumTimeInterval property of the class, if not provided a default value of 0 is used for the property
  • customStorage: Storage - Optional custom storage to be used instead of the default one utils/storage.js

Example

To get an instance of VASTClient, simply import it and create one using the constructor:

import { VASTClient } from 'vast-client'

// With default values
const vastClient = new VASTClient();

// With cappingFreeLunch
const vastClient = new VASTClient(2);

// With cappingMinimumTimeInterval
const vastClient = new VASTClient(0, 2000);

// With customStorage
const vastClient = new VASTClient(0, 0, customStorage);

Properties

cappingFreeLunch: Number

The number of calls to skip.

Example: if set to 3, the first 3 VAST requests will not be executed.

// Ignore the first 2 calls
vastClient.cappingFreeLunch = 2;

// Those following vastClient.get calls won't be done
vastClient.get(VASTUrl);
vastClient.get(VASTUrl);

// VASTUrl will be called
vastClient.get(VASTUrl);

cappingMinimumTimeInterval: Number

The minimum time interval (in milliseconds) which has to pass between two consecutive calls.

Example: if set to 2000, any call which will be requested less than 2 seconds after the last successful one will be ignored.

// Ignores any call made 5 minutes or less after one.
vastClient.cappingMinimumTimeInterval = 5 * 60 * 1000;

// The call is made
vastClient.get(VASTUrl);

// 2 minutes later: The call is ignored
vastClient.get(VASTUrl);

// d minutes later: The call is made
vastClient.get(VASTUrl);

storage: Storage

Instance of a class which implements the Storage interface. Should be set up only once through the constructor.

Public Methods 💚

get(url, options): Promise

Gets a parsed VAST document for the given url, applying the skipping rules defined (cappingFreeLunch and cappingMinimumTimeInterval).

Returns a Promise which either resolves with the fully parsed VASTResponse or rejects with an Error.

By default the fully parsed VASTResponse contains all the Ads contained in the VAST resource. It's possible to get only the first Ad or AdPod and then get the remaining ones on demand by passing resolveAll: false in the options parameter.

Parameters

  • url: String - The url to use to fecth the VAST document
  • options: Object - An optional Object to configure the request:
    • timeout: Number - A custom timeout for the requests (default 0)
    • withCredentials: Boolean - A boolean to enable the withCredentials options for the XHR and FLASH URLHandlers (default false)
    • wrapperLimit: Number - A number of Wrapper responses that can be received with no InLine response (default 0)
    • urlHandler: URLHandler - Custom urlhandler to be used instead of the default ones urlhandlers
    • urlhandler: URLHandler - Fulfills the same purpose as urlHandler, which is the preferred parameter to use
    • resolveAll: Boolean - Allows you to parse all the ads contained in the VAST or to parse them ad by ad or adPod by adPod (default true)

Example

const vastClient = new VASTClient();

vastClient.get('http://example.dailymotion.com/vast.xml')
  .then(res => {
    // Do something with the parsed VAST response
  })
  .catch(err => {
    // Deal with the error
  });

// With the options optional parameter
const options = {
  withCredentials: true,
  wrapperLimit: 7
};

vastClient.get('http://example.dailymotion.com/vast.xml', options)
  .then(res => {
    // Do something with the parsed VAST response
  })
  .catch(err => {
    // Deal with the error
  });

How does resolveAll work

Let's consider the VAST shown in the following image: it contains 4 ads, with the 2nd and 3rd defining an AdPod.

AdPod example

Using get method with default options will return a VASTResponse containing all the ads resolved, which would look like this:

{
  ads: [
    ad1,
    ad2,
    ad3,
    ad4
  ],
  errorURLTemplates,
  version
}

The resolveAll parameter allows to request only the first Ad or AdPod. If we pass it as false the response would look like:

{
  ads: [
    ad1
  ],
  errorURLTemplates,
  version
}

We can then request the remaining ads using getNextAds method:

// get the next ad or adPod
vastClient.getNextAds()
  .then(ads => {
    console.log(ads);

    /*
    Will print something like

    {
      ads: [
        ad2,
        ad3
      ],
      errorURLTemplate
    }
    */
  });

// get al the remaining ads
vastClient.getNextAds(true)
  .then(ads => {
    console.log(ads);

    /*
    Will print something like

    {
      ads: [
        ad2,
        ad3,
        ad4
      ],
      errorURLTemplate
    }
    */
  });

Why should you use resolveAll=false?

Most times you will only need the first Ad or AdPod (following ones are usually either optional ads or fallback ones). Using resolveAll=false allows you to avoid useless calls to resolve every wrapper chain of the initial VAST.

hasRemainingAds(): Boolean

Returns true if there are remaining ads not returned by the get method (in case resolveAll was passed as false). Returns false otherwise.

Example

const vastClient = new VASTClient();

// With the options optional parameter
const options = {
  resolveAll: false
};

// Getting a VAST which contains more than one Ad
vastClient.get('http://example.dailymotion.com/vast.xml', options)
  .then(res => {
    // Do something with the parsed VAST response
  })
  .catch(err => {
    // Deal with the error
  });

vastClient.hasRemainingAds(); // Returns true

getNextAds(all): Promise

Returns a Promise which either resolves with a VASTResponse or rejects with an Error. The resolved VASTResponse can contain either a single Ad or AdPod or all the remaining Ads if all parameter is passed as true.

Example

const vastClient = new VASTClient();

// With the options optional parameter
const options = {
  resolveAll: false
};

// Getting a VAST which contains more than one Ad
vastClient.get('http://example.dailymotion.com/vast.xml', options)
  .then(res => {
    // Do something with the parsed VAST response
  })
  .catch(err => {
    // Deal with the error
  });

vastClient.hasRemainingAds(); // Returns true

vastClient.getNextAds()
  .then(res => {
    // Do something with the next Ads
  })
  .catch(err => {
    // Deal with the error
  });


vastClient.getNextAds(true)
  .then(res => {
    // Do something with all the remaining Ads
  })
  .catch(err => {
    // Deal with the error
  });

getParser()

Returns the instance of VASTParser used by the client to parse the VAST. Use it to directly call a method provided by the VASTParser class.

const vastClient = new VASTClient();
const vastParser = vastClient.getParser();

// Clear the url template filters used
vastParser.clearUrlTemplateFilters();