Javascript library .getAttr() function not working? - attributes

Question

I am working on my own javascript library. The library has a getAttr() function that operates like this:tex(selector).getAttr(name); Here is the library's code:
(function(){
var tex = function(s){
return new tex.fn.init(s);
};
tex.fn = tex.prototype ={
init : function(s){
if(!s){
return this;
}
else{
this.length = 1;
if (typeof s === "object"){
this[0] = s;
}
else if(typeof s === "string"){
var obj;
obj = document.querySelector(s);
this[0] = obj;
}
return this;
}
}
}
tex.fn.init.prototype = tex.fn;
tex.fn.init.prototype = {
attr : function(name, value){
/*if(name && !value){
return this[0].getAttribute(name);
}else if(name && value){
this[0].setAttribute(name,value);
};*/
this[0].setAttribute(name,value);
},
getAttr : function(name){
return this[0].getAttribute(name);
},
removeAttr : function(name){
this[0].removeAttribute(name);
},
print : function(txt){
this[0].innerHTML = txt;
}
};
window.TechX = tex;
})();
Here is the code in the body section:
<nav>
<ul>
<li><a id="MainDropper">Pick your method:</a>
<ul>
<li><a>book</a>
<ul>
<li><a data-val="Book" href="javascript:setType(this)">Book</a></li>
</ul>
</li>
</ul>
</li>
</ul>
</nav>
And here is my code in the head section:
function setType(obj){
tex("#MainDropper").print(tex(obj).getAttr("data-val"));
}
So when I click the book link the mail dropper should have the text "Book." But instead I get an error in the library that says, "the [object global] has no method getAttrribute." Does anyone know how I can fix this problem?
Thank you so much.

Answer 1

The credit should really go to Bergi, but in the interest of providing an answer, here goes.
When you use a listener like:
<a onclick="code" ... >
then the content of the onclick attribute is effectively wrapped in a function that is called with the element as this, like:
function listener(){code}
listener.call(element);
However, when the href attribute and javascript pseudo–protocol (aka "javascript: URL scheme") are used the code is executed as global code, so more or less just:
code;
HTML5 says to behave as if a new script element was inserted with the code as content. So within the listener function (execution context), this will reference the global (window) object.
Note that browser behaviour can differ here (e.g. variables declared in javascript URLs) as there was no specification for how such code should be treated until HTML5, which really just tries to specify one version of what browsers already do. Previously, it was left as part of DOM 0*, which was all the DOM stuff that browsers did before W3C specifications that was not made part of new specifications.
* DOM 0 is "…a mix (not formally specified) of HTML document functionalities offered by Netscape Navigator version 3.0 and Microsoft Internet Explorer version 3.0." W3C DOM Level 1 01-Oct-1998.