JSFiddle - React, Tailwind, and code Playground

JavaScript

function x(y,a,b,c,d,e,f,g,h,i,k,l,m){
  a=y%19
  b=~~(y/100)
  c=y%100
  d=~~(b/4)
  e=b%4
  f=~~((b+8)/25)
  g=~~((b-f+1)/3)
  h=(19*a+b-d-g+15)%30
  i=~~(c/4)
  k=c%4
  l=(32+2*e+2*i-h-k)%7
  m=~~((a+11*h+22*l)/451)
  return y+'-'+~~((h+l-7*m+114)/31)+'-'+((h+l-7*m+114)%31+1)
}

document.body.innerHTML = x(2012)