Convert cover.js to es6
Convert cover.js to es6

aswathyjacob8/newtest,ironhack/hackmd,Rwing/hackmd,hackmdio/hackmd,Yukaii/hackmd,jccrofty30/hackmd,Rwing/hackmd,hackmdio/hackmd,PeterDaveHello/hackmd,jackycute/HackMD,PeterDaveHello/hackmd,Rwing/hackmd,ironhack/hackmd,jackycute/HackMD,PeterDaveHello/hackmd,jackycute/HackMD,Yukaii/hackmd,Yukaii/hackmd,jccrofty30/hackmd,jccrofty30/hackmd,hackmdio/hackmd,aswathyjacob8/newtest,aswathyjacob8/newtest,ironhack/hackmd