level.js
/**
* http://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html#visual-audio-contrast-contrast-73-head
*
* @module color-measure/level
*/
var contrast = require('./contrast');
module.exports = function (color1, color2) {
var contrastRatio = contrast(color1, color2);
return (contrastRatio >= 7.1) ? 'AAA' : (contrastRatio >= 4.5) ? 'AA' : '';
};