gradient background javascript

	// ======================================= Random Gradient Backgroud ======================================
	function animiatedGradientBackground(selector){
		var colors = array_shuffle(new Array(
		  [62,35,255],
		  [60,255,60],
		  [255,35,98],
		  [45,175,230],
		  [255,0,255],
		  [255,128,0]));
		var step = 0;
		//color table indices for:
		// current color left
		// next color left
		// current color right
		// next color right
		var colorIndices = [0,1,2,3];
		//transition speed
		var gradientSpeed = 0.002;
		updateGradient(selector,step,colors,colorIndices,gradientSpeed);
	}
		function updateGradient(selector,step,colors,colorIndices,gradientSpeed){
			if ( $===undefined ) return;

			var c0_0 = colors[colorIndices[0]];
			var c0_1 = colors[colorIndices[1]];
			var c1_0 = colors[colorIndices[2]];
			var c1_1 = colors[colorIndices[3]];

			var istep = 1 - step;
			var r1 = Math.round(istep * c0_0[0] + step * c0_1[0]);
			var g1 = Math.round(istep * c0_0[1] + step * c0_1[1]);
			var b1 = Math.round(istep * c0_0[2] + step * c0_1[2]);
			var color1 = "rgb("+r1+","+g1+","+b1+")";

			var r2 = Math.round(istep * c1_0[0] + step * c1_1[0]);
			var g2 = Math.round(istep * c1_0[1] + step * c1_1[1]);
			var b2 = Math.round(istep * c1_0[2] + step * c1_1[2]);
			var color2 = "rgb("+r2+","+g2+","+b2+")";

			$(selector).css({
			   background: "-webkit-gradient(linear, left top, right top, from("+color1+"), to("+color2+"))"}).css({
				background: "-moz-linear-gradient(left, "+color1+" 0%, "+color2+" 100%)"});

			step += gradientSpeed;
			if ( step >= 1 )
			{
				step %= 1;
				colorIndices[0] = colorIndices[1];
				colorIndices[2] = colorIndices[3];

				//pick two new target color indices
				//do not pick the same as the current one
				colorIndices[1] = ( colorIndices[1] + Math.floor( 1 + Math.random() * (colors.length - 1))) % colors.length;
				colorIndices[3] = ( colorIndices[3] + Math.floor( 1 + Math.random() * (colors.length - 1))) % colors.length;
			}
		}
	// ========================================================================================