Javascript convert RGB and RGBA to Hex, any format

any_rgb_to_hex.js

/**
 * Convert RGB to Hex. Allows whitespace. If given hex, returns that hex. Alpha opacity is discarded.
 * Supports formats:
 * #fc0
 * #ffcc00
 * rgb( 255, 255, 255 )
 * rgba( 255, 255, 255, 0.5 )
 * rgba( 255 255 255 / 0.5 )
 */
function rgb_any_to_hex( orig ) {	
	var regex_hex, regex_trim, color, regex_rgb, matches, hex;
	
	// Remove whitespace
	regex_trim = new RegExp(/[^#0-9a-f\.\(\)rgba]+/gim);
	color = orig.replace( regex_trim, ' ' ).trim();
	
	// Check if already hex
	regex_hex = new RegExp(/#(([0-9a-f]{1})([0-9a-f]{1})([0-9a-f]{1}))|(([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2}))/gi);
	if ( regex_hex.exec( color ) ) {
		return color;
	}
	
	// Extract RGB values
	regex_rgb = new RegExp( /rgba?\([\t\s]*([0-9]{1,3})[\t\s]*[, ][\t\s]*([0-9]{1,3})[\t\s]*[, ][\t\s]*([0-9]{1,3})[\t\s]*([,\/][\t\s]*[0-9\.]{1,})?[\t\s]*\);?/gim );
	matches = regex_rgb.exec( orig );
	
	if ( matches ) {
		hex = 
			'#' +
			(matches[1] | 1 << 8).toString(16).slice(1) +
			(matches[2] | 1 << 8).toString(16).slice(1) +
			(matches[3] | 1 << 8).toString(16).slice(1);
		return hex;
	}else{
		return orig;
	}
}

Test usage (including the above function):

var colors = [];

// Test inputs:
colors.push( "rgb\( 128, 255, 100 \);" );
colors.push( "rgb\( 200, 30, 5 \);" );
colors.push( "rgba\( 128, 255, 100, 0.25 \);" );
colors.push( "rgba\( 200, 30, 5, 0.5 \);" );
colors.push( "rgb\(128,255,100\);" );
colors.push( "rgb\(200, 30,5 \);" );
colors.push( "rgba\(128, 255, 100, 0.25\);" );
colors.push( "rgba\( 200,30,5, 0.5 \);" );
colors.push( "#ffcc00" );
colors.push( "#fc0" );
colors.push( "rgba\( 125 12 5 / 0.5 \);" );
colors.push( "rgba\(125 12 5/0.5\);" );
colors.push( "      rgb\( 128, 255, 100 \)" );
colors.push( "		rgb\( 200, 30, 5 \)" );
colors.push( "	 	rgba\(128, 255, 100, 0.25\)" );
colors.push( "  	  rgba\( 200,30,5, 0.5 \)" );
colors.push( "	 #ffcc00" );
colors.push( " 	#fc0" );
colors.push( "    rgba\( 125 12 5 / 0.5 \)                " );
colors.push( "			rgba\(125 12 5 / 0.5\)	 	" );


let new_colors = [];
for ( var i in colors ) {
	let color = colors[i];
	let hex = rgb_any_to_hex( color );
	new_colors.push({'old': color, 'new': hex});
}

console.table( new_colors );

Output: