Automated Readability Index, Flesch-Kincaid (ease/level), Gunning-Fog, SMOG Index, Coleman-Liau
> const testPhrase = 'No kidding - Lorenzo called off his trip to visit Mexico City just because they told him the conquistadores were extinct.';
> Readability.automatedReadability(testPhrase);
11.274285714285718
> Readability.smog(testPhrase);
10.065306667255596
> Readability.gunningFog(testPhrase);
14.114285714285714
> Readability.colemanLiau(testPhrase);
11.952857142857141
> Readability.fleschKincaid(testPhrase);
{ ease: 52.57714285714289, gradeLevel: 11.142857142857142 }