JavaScript that creates CSS media queries for responsive font sizing

responsive-font-sizing.js

function responsiveFontSizing( config ) {
	var mediaQueryType = ( config && config.mediaQueryType ) || 'min-width';
	var widthBegin = ( config && config.widthBegin && parseFloat( config.widthBegin, 10 ) ) || 17;
	var widthEnd = ( config && config.widthEnd && parseFloat( config.widthEnd, 10 ) ) || 34;
	var fontSizeBegin = ( config && config.fontSizeBegin && parseFloat( config.fontSizeBegin, 10 ) ) || 2;
	var fontSizeEnd = ( config && config.fontSizeEnd && parseFloat( config.fontSizeEnd, 10 ) ) || 4;
	var lineHeightBegin = ( config && config.lineHeightBegin && parseFloat( config.lineHeightBegin, 10 ) ) || 1.25;
	var lineHeightEnd = ( config && config.lineHeightEnd && parseFloat( config.lineHeightEnd, 10 ) ) || 1.0625;
	var selector = ( config && config.selector ) || 'h1';
	var unit = ( config && config.unit ) || 'em';
	var css = [];
	for( var i = widthBegin; i <= widthEnd; i++ ) {
		var fontSize = fontSizeBegin + ( fontSizeEnd - fontSizeBegin ) * ( i - widthBegin ) / ( widthEnd - widthBegin );
		var lineHeight = lineHeightBegin + ( lineHeightEnd - lineHeightBegin ) / ( widthEnd - widthBegin ) * ( i - widthBegin );
		css.push(
			'@media only screen and (' + mediaQueryType + ': ' + i + unit + ') { ' +
				selector + ' { font-size: ' + fontSize + unit + '; line-height: ' + lineHeight + '; }' +
			' }'
		);
	}
	return css; // array of strings
}