It isn't missing. Javascript was created to serve a specific purpose, which didn't include left-padding text in a terminal. Most language I'm aware of wouldn't have that in their standard lib.
If you want Javascript to act as a drop-in replacement for C++ or Java or some other general programming language (which Javascript was never intended to be) don't act as if needing to write libraries to cover that missing functionality is a problem with the language. You're using the wrong tool for the wrong job.
> Most language I'm aware of wouldn't have that in their standard lib.
Python has str.ljust [1] (and str.rjust [2]):
> Return the string left justified in a string of length width. Padding is done using the specified fillchar (default is an ASCII space). The original string is returned if width is less than or equal to len(s).
Ruby and PHP both have string padding functions. So does Swift. (edit: and as Macha points out, C and any language with printf functionality, like Perl.) It’s not that uncommon.
(I was going to joke that TRS-80 BASIC had it circa 1979, but it turns out that it would be a two-step operation: Python’s str.ljust(40) would become LEFT$(STRING$(40, " "),40) .)
C has it in their standard library, basically forever. See the list of specifiers to printf. C! If it fits into the C standard library, it's not bloating the Javascript standard library.
If you want Javascript to act as a drop-in replacement for C++ or Java or some other general programming language (which Javascript was never intended to be) don't act as if needing to write libraries to cover that missing functionality is a problem with the language. You're using the wrong tool for the wrong job.