Monday, September 21, 2009

One Function To Trap Them All

This is a quick one. This technique could have some side-effect I am not aware about but I've never seen it so far in any library. Talking about LiveMonitor I have successfully tested same concept to create faster implementation of some of my DOM common code, not yet updated in vice-versa.

document.getElementsByClassName Example


/* Another (C) WebReflection Silly Idea */

// how to re-use them all, just an example
document.getElementsByClassName = function getElementsByClassName(className){
re = new RegExp("(?:\\s|^)" + className + "(?:\\s|$)"),
ret = [], i = 0, l = 0, length = childNodes.length, node;
i < length; ++i
if((node = childNodes[i]).nodeType === 1 && re.test(node.className))
ret[l++] = node
return ret;

// let the magic happen

What we have here?
  1. A trapped live object, probably used in 90% of selector libraries, but performed via scope resolution (the document) and a function execution (the getElementsByTagName method) over all nodes ("*")
  2. a theoretically zero performances impact to retrieve again every node, being live there is no need to refresh it, and being trapped run-time, it will contain few nodes during the first execution
  3. a single scope able to create N functions based on one of the most common created HTMLCollection

What do you think?

No comments:

Post a Comment