Emulating div contentEditable = "true" with textarea

[jimmyoneshot]

I'm trying to emulate exactly how a div with the attribute contentEditable = "true" would operate using a textarea...trying and failing. I found some code somewhere which attempts to do something like his but it isn't working well for me.

 

I want to do this without jquery and with javascript only. The best example I can think of is Facebook's text area that you use to write on somebody's wall.

 

Here's my sizing function

 

function sz(t) {
a = t.value.split('\n');
b=1;
for (x=0;x < a.length; x++) { if (a[x].length >= t.cols) b+= Math.floor(a[x].length/t.cols);
}
b+= a.length;
if (b > t.rows) t.rows = b;
}

 

and here's my text area:-

 

<textarea id="text_entry" rows="1" cols="1" onkeyup="sz(this)" >User text goes here</textarea>