Tag Archives: code snippet

null vs. undefined (javascript)

Aside

how well do you know your “null”s and “undefined”s?

write down what you expect the result of each operation to be. run them in a javascript console (Chrome, Firefox/Firebug, Safari). compare, verify, contrast, and, for fun, give yourself a score out of “3/4 donut”.

// Equality
null == undefined
null === undefined
!null == !undefined
!null === !undefined

// addition and concatenation
null + ''
undefined + ''
null + 1
undefined + 1

// fun with enumerations
test = []; test.push(null); console.log(test)
test = []; test.push(undefined); console.log(test)
{null:2}
{undefined:2}
{a:null}
{a:undefined}
[More programming riddles]

recursive touch

Aside

i just moved a bunch of media files from one device, to the other, and the file creation dates for a small number of my directories (and their contents) moved a few years into the future.

this problem smelled like a python 1 liner; i came pretty close – highlight to see the code:


import os, sys, subprocess

for d,s,fs in os.walk(sys.argv[1]):
    for p in (s+fs):
        subprocess.call(["touch",os.path.join(d,p)])

(source online, in case I improve it)

[More programming riddles]