Print unique timestamps on a for loop

If you try to print the timestamp on a for loop, probably you'll get repeated results as the computer performs the operations in less than 1 ms.

Example:

javascript
for(let i = 0; i < 1000; i ++){
    console.log(Date.now())
}

/* The printed timestamp repeats itself several times
6 1633102772083
25 1633102772084
25 1633102772085
28 1633102772086
13 1633102772087
28 1633102772088
...
*/

The trick to make the printed results unique is to append the index at the end.

Example:

javascript
for(let i = 0; i < 1000; i ++){
    console.log(`${Date.now()}${i}`)
}

/* The approach looks good for the first 10 numbers
16331035373630
16331035373631
16331035373632
16331035373633
16331035373634
16331035373635
16331035373636
16331035373637
16331035373638
16331035373639
163310353736310 |
163310353736311 |---- But, you have a problem from here on
163310353736312 |
...
*/

To solve the previous issue, you need to append some zeros at the beginning of the indexes.

Example:

javascript
for(let i = 0; i < 1000; i ++){
    console.log(`${Date.now()}${i.toString().padStart(4, '0')}`)
    //                                         --
    //                                          index.toString().length is more generic
}

/* Now every number has equal lenght and they are sorted
16331039674280000
16331039674280001
16331039674280002
16331039674280003
16331039674280004
16331039674280005
16331039674280006
16331039674280007
16331039674280008
16331039674280009
16331039674280010
16331039674280011
16331039674280012
16331039674280013
*/

Bear in mind that you are adding some microsegonds (µs) to the real timestamp.