Buffer's indexOf does not seem to handle numbers correctly

[Sha-Bang]

• Version: v4.4.7
• Platform: Linux hostname 3.13.0-91-generic src: redo unaligned access workaround #138-Ubuntu SMP Fri Jun 24 17:00:34 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Node seems to behave oddly when using indexOf (or includes) on a buffer

It seems that when a string or buffer is the parameter of indexOf it returns the index of the first byte that matches it; however, when a number is passed in it returns the index of the last byte that matched it, unless there are duplicates, then it behaves very oddly.

$ node
> buf = new Buffer('this is a test');
 <Buffer 74 68 69 73 20 69 73 20 61 20 74 65 73 74>
> buf.indexOf('is') // pass
2
> buf.indexOf(new Buffer('is')) // pass
2
> buf.indexOf(new Buffer('istest')) // pass
-1
> buf.indexOf('istest') // pass
-1
> buf.indexOf(0x6973) // odd 
3
> buf.indexOf(0x697320) // appears to return the index of the last byte that matched the number given
4
> buf.indexOf(0x69732069) // unless there are duplicates, then it does weird things
2
> buf.indexOf(0x697374657374) 
0
> buf.indexOf(0x69737374)
0
> buf.indexOf(0x69737465)
11

[addaleax]

I think this is the intended behaviour, because .indexOf() converts the argument to an 8-bit integer, i.e. it truncates 0x69737374 to 0x74.

[jasnell]

@nodejs/buffer

[jasnell]

Yes, this seems to be the correct behavior