$ node .

process.stdout.write('long message first')
process.stdout.write('short message')
process.stdout.write('\n')

long message firstshort message

process.stdout.write('long message first\n')
process.stdout.write('short message\n')

long message first
short message

process.stdout.write('long message first\r')
process.stdout.write('short message\n')

short messagefirst

Hmm, need to clear the line. Let's use process.stdout.columns to know how much to clear.

console.log('stdout width', process.stdout.columns)
const emptyLine = ''.padEnd(process.stdout.columns, ' ')
process.stdout.write('long message first\r')
// delay to better see the first message
setTimeout(() => {
  process.stdout.write(emptyLine + '\r')
  process.stdout.write('short message\n')
}, 1000)

stdout width 99
long message first
# then a second later just
short message

Docker

FROM node:8
COPY index.js .
RUN node .

Status: Downloaded newer image for node:8
 ---> ed145ef978c4
Step 2/3 : COPY index.js .
 ---> 44db58d93738
Step 3/3 : RUN node .
 ---> Running in 1bc9d0e3b0d3
stdout width undefined
short messagefirst
Removing intermediate container 1bc9d0e3b0d3
 ---> cb8ac000c993
Successfully built cb8ac000c993

There is no process.stdout.columns number! So how do we show the second line? Well, we can take a shortcut and just do the "newline" instead!

const emptyLine = process.stdout.columns ? ''.padEnd(process.stdout.columns, ' ') : '\n'

and it works nicely in the terminal and in Docker

 ---> Running in 8d63833b96ac
stdout width undefined
long message first
short message

Nice, except when you have progress bars ... which output thousands of messages when showing percentage increments for example. In that case treat progress bars as an enhancement. By default only show text messages at the start and end of the action. If there is process.stdout.columns then you have a more capable terminal and you can render messages in place, and you can use progress indicators.