V3 is a modernized version of a highly used JavaScript SDK. Prior versions of the SDK assumed form-based environments. To meet the needs of the modern Web, v3 was built to adapt to a wide variety of scenarios (including single-page apps with JavaScript-heavy checkout). No longer will merchants without a form-based environment need to hack together a workaround in order to use an SDK that assumes forms. Read the full details
http://www.programmableweb.com/news/paypal-introduces-braintree-javascript-sdk-v3/brief/2016/12/18
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