Joe Song

Turns out that the default universal code for Disqus won’t work in IE (8 or below at time of writing). The cause is a line (#1189 to be exact) in their thread.js that calls the indexOf method on an array.

As we all know, IE doesn’t support the indexOf method for the Array prototype. The simple solution is add indexOf support in IE. Here’s the code:

// add indexOf to arrays in IE
if (!Array.prototype.indexOf){
	Array.prototype.indexOf = function(elt /*, from*/)  {
		var len = this.length;
		var from = Number(arguments[1]) || 0;
		from = (from < 0)
			? Math.ceil(from)
			: Math.floor(from);
		if (from < 0)
			from += len;
		for (; from < len; from++)
		{
			if (from in this &&
					this[from] === elt)
				return from;
		}
		return -1;
	};
}