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I might be wrong but isn't that part of the .NET framework and won't work in regular Javascript functions.
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I might be wrong but isn't that part of the .NET framework and won't work in regular Javascript functions.

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<div class="content wysiwyg-content">
I am using a peice of javascript which has <br />
<br />
ys.WebForms.PageRequestMan<wbr />ager.getIn<wbr />stance()<br />
<br />
I am getting the following error <br />
<br />
Sys us undefined.<br />
<br />
I am not sure what to do?
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I am using a peice of javascript which has 

ys.WebForms.PageRequestManager.getInstance()

I am getting the following error 

Sys us undefined.

I am not sure what to do?

sys is undefined

JavaScript is a dynamic, object-based language commonly used for client-side scripting in web browsers. Recently, server side JavaScript frameworks have also emerged. JavaScript runs on nearly every operating system and  in almost every mainstream web browser.

JavaScript

JScript is Microsoft's dialect of the ECMAScript standard that is used in Microsoft's Internet Explorer. JScript is implemented as an Active Scripting engine, so it can be "plugged in" to OLE Automation applications that support Active Scripting, such as Internet Explorer, Active Server Pages, and Windows Script Host. It also means such applications can use multiple Active Scripting languages, e.g., JScript, VBScript or PerlScript.

JScript

Asynchronous JavaScript and XML (AJAX) is a group of interrelated Web development techniques used on the client-side to create asynchronous Web applications. With AJAX, web applications can send data to and retrieve from a server asynchronously (in the background) without interfering with the display and behavior of the existing page. HTML and CSS can be used in combination to mark up and style information. The Document Object Model (DOM) is accessed with JavaScript to dynamically display and allow interaction with the information presented.