AJAX Toolkit Developer Guide
Embed API calls in Visualforce pages, buttons, and links with AJAX Toolkit — a
JavaScript wrapper around SOAP API.
The AJAX Toolkit supports Microsoft® Internet Explorer® versions 9, 10, and 11 with the latest Microsoft hot fixes applied, and Mozilla® Firefox®, most recent stable version. The AJAX Toolkit is based on the partner WSDL. Because there’s no type checking in JavaScript, the type information available in the enterprise WSDL isn’t needed.