99 bottles of beer as short as possible in ECMAScript 6 - currently 142 characters

99bottles.js

x=""
b=r=>`${c||"No more"} bottle${c-1?"s":""} of beer${r&&c--||" on the wall"}
`
for(c=99;c;)x+=b()+b(1)+`Take one down, pass it around
`+b()

159:

b=(c,r)=>`${c||"No more"} bottle${c-1?"s":""} of beer${r?"":" on the wall"}`,v=c=>!c||`${b(c)}
${b(c,1)}
Take one down, pass it around
${b(--c)}
${v(c)}`
v(99)

154:

x=""
for(c=99;c;){
b=r=>`${c||"No more"} bottle${c-1?"s":""} of beer${r?c--||"":" on the wall"}`
x+=b()+`
${b(c)}
Take one down, pass it around
${b()}
`}x

Do you even need to declare x=""?

@abdullin yeah, ReferenceError

152:

b=r=>`${c||"No more"} bottle${c-1?"s":""} of beer${r?c--||"":" on the wall"}`,x=""
for(c=99;c;)x+=b()+`
${b(1)}
Take one down, pass it around
${b()}
`
x

150 (don't need the x at the end to print)

b=r=>`${c||"No more"} bottle${c-1?"s":""} of beer${r?c--||"":" on the wall"}`,x=""
for(c=99;c;)x+=b()+`
${b(1)}
Take one down, pass it around
${b()}
`

148 (forgot an easy one)

b=r=>`${c|"No more"} bottle${c-1?"s":""} of beer${r?c--|"":" on the wall"}`,x=""
for(c=99;c;)x+=b()+`
${b(1)}
Take one down, pass it around
${b()}
`

147 - almost tweetable!

x=""
for(c=99;c;)
b=r=>`${c||"No more"} bottle${c-1?"s":""} of beer${r?c--||"":" on the wall"}
`,x+=b()+b(1)+`Take one down, pass it around
`+b()
x

@ToJans don't forget to change || by |

142 chars!

x=""
b=r=>`${c|"No more"} bottle${c-1?"s":""} of beer${r?c--|"":" on the wall"}
`
for(c=99;c;)x+=b()+b(1)+`Take one down, pass it around
`+b()

You can't change || by |, or the last sentence is wrong; so back to 143 chars...