rwx rwx rwx
111 111 111

rwx r-x r--
111 101 100


100 = ?
  |
  2^0 = 1
 |
 2^1 = 2
|
2^2 = 4

100 in binary = 5 in decimal


rwx r-x r--
111 101 100
7   5	4

chmod 754 filename.js