Javascript Octal escape character (8 binary) _javascript tips

During the groping process, see such characters as "\155", used in place of the character "M". Why? .... Completely do not know the reason, the whole person suddenly panic! Don't say your 4 years of experience! "\155" and "M" is congruent, until now, 2011 years ago I know, deeply ashamed!

For character escape, the common is probably as follows:

"\u5230" ==> "to"
"\ t" ==> horizontal tab "\u0009"
"\" ==> backslash "\u005c"
"\x35" ==> "5"
....

155 converted from 8 to 10 to 1*64+5*8+5=109
String.fromCharCode (109) = = "M"

There are 256 or 8 binary and 16 escape characters in total

The 16-in-system escape character has a fixed format (2 digits):
\x Hexdigit Hexdigit

8 can have 1-3 digits, the maximum is "\377", in ECMA 262v5 did not find the relevant introduction, guess the way to get string value (SV) is the following steps:

1: Get character values (CV) length value of Len
2:len=math.min (len,3)
3: Check the length of Len after the escape character, whether it conforms to the 8 system, meet the 5th step, or step 4th
4:len--, to step 3rd.
5: Conversion to get the corresponding character s0 and Len bit after the character phase

"\1568a" = "n8a"
"\0578a" = "/8a"