With the constant influx of JavaScript programmers, it keeps worth repeating that you should always run JavaScript in strict mode via "use strict"; (like in the past Visual Basic 6 developers should use option strict and option explicit) to forget risky JavaScript syntax like implicit ocal constants (which were removed from the documentation in the 2009 ECMAScript 5 specification for JavaScript), and every codeline should have a test code covering it, especially for comparisons involving non-strict behaviour like the use of leading zeros.
As of the succeeding 2015 standard (ECMAScript 6), octal numbers in JavaScript start with 0o or 0O followed by a series of octal digits.
Oh, and the history of octal in computing of course has to do with 6-bit systems and also lead to 6-six bit character codes including BCD character encoding..
My tweet back earlier this year: [WaybackSave/Archive] Jeroen Wiert Pluimers @wiert@mastodon.social on X: “@_ObomheseR Since JavaScript is in the group of curly based programming languages influenced by the B programming language, integer constants starting with zero are tried first in octal base. 017 octal is 15 decimal 018 octal is not possible, so becomes 18.”
Inhteritence:
The Wiert Corner - irregular stream of stuff 