Add markers to text to easily see line length when prototyping layouts.

markers.js

(function(doc){
	if(doc.querySelectorAll) { // This only works in IE 8+
        var copy = doc.querySelectorAll('.string') // Element(s) with class="string" need to be in markup
	,	i = 0
	,	ii = copy.length
	,	replace_at = function(text, index, char) {
			return text.substr(0, index) + char + text.substr(index + 1);
		}
	;

	for(i; i<ii; i++) {
		var text = copy[i].textContent;

		text = replace_at(text, 44, '^'); // Replace 45th char with asterisk
		text = replace_at(text, 71, '$'); // Replace 72nd char with caret
    		text = replace_at(text, 66, '*'); // Replace 66th char with asterisk

		copy[i].textContent = text;
	}
}
})(document);