How to access textarea's value through javascript in ASP.NET?

I have a textarea and i am using a plugin for that textarea. In that plugin there is a function getCode() which will return the value of the textarea. That function will be called like - textarea_id.getCode();

I am using ASP.NET in which i have declared the textarea (runat=server), and the textarea'a id i can get but when i am writing the following code it is not calling the method.

'<%= txtName.ClientID %>'.getCode(); 

But if i am writing then it is working fine.

ctrl001_txtxName.getCode();

Because the first one is a string and the second one i guess is an object. If so then how to overcome this problem. Can 开发者_运维知识库anyone please help?

Code Block

Plugin = function(obj)
{
    var self = document.createElement('iframe');
    self.textarea = obj;
    self.textarea.disabled = true;
    self.textarea.style.overflow = 'hidden';
    self.style.height = self.textarea.clientHeight + 'px';
    self.style.width = self.textarea.clientWidth + 'px';
    self.textarea.style.overflow = 'auto';
    self.style.border = '1px solid gray';
    self.frameBorder = 0; // remove IE internal iframe border
    self.style.visibility = 'hidden';
    self.style.position = 'absolute';
    self.options = self.textarea.className;

    self.initialize = function()
    {
        self.editor = self.contentWindow.CodePress;
        self.editor.body = self.contentWindow.document.getElementsByTagName('body')[0];
        self.editor.setCode(self.textarea.value);
        self.setOptions();
        self.editor.syntaxHighlight('init');
        self.textarea.style.display = 'none';
        self.style.position = 'static';
        self.style.visibility = 'visible';
        self.style.display = 'inline';
    }

    self.getCode = function()
    {
        return self.textarea.disabled ? self.editor.getCode() : self.textarea.value;
    }

    return self;
}

document.getElementById('<%= txtName.ClientID %>').getCode();