The tag means: "The browser may insert a line break here, if it wishes." It the browser does not think a line break necessary nothing happens" - Check the overhauling on ppk.

If you type a looooooooooooooooong word on google talk of Gmail it injects tags from 15 by 15. We know there is a lot of ways to write a solution to do it, some of them looking for a better performance another looking for elegance.

I was wondering how is the best way to insert tags inside a long string, off course, the solution can be used to insert any piece of string inside another.

The first solution I found have a better performance:

function wbr(str, r) {
	r = r || 15;
    var t = str.length, out = "";
   
    for (var i = 0; i < Math.ceil(t/r); i++)
        out = [ out, [str.slice(i*r, i*r+r), i*r+r >= t ? "" : ""].join("") ].join("");
   
    return out;
};

The second, is more elegant, but have a worse performance:

function wbr2(str) {
	var wbr = "", r = arguments[1] || 15, i = 1, out = "";
	
	str.replace(/(.{1})/g, function(piece) {
		out = [out, piece, i++%r==0 ? wbr : "" ].join("");
	});
	
	return out;
} 

Trying some of the functions above:

Do you have another intresting way to do this injection?
I'm eager to know your ideas!

After a quick chat with John Resig he gave me in amazing 3 minutes another way to do it, check his idea below: (thanks John!)