javascript - Node.js: Cannot set a value '0xff' by 'buf.writeIntBE()' -


i can write -1 buffer writeintbe, code is:

var b = new buffer(1); b.writeintbe(-1, 0, 1); console.log(b); //<buffer ff>

however, following code not functional

var b = new buffer(1); b.writeintbe(0xff, 0, 1); console.log(b);

the error code :

buffer.js:794     throw new typeerror('value out of bounds');     ^  typeerror: value out of bounds     @ checkint (buffer.js:794:11)     @ buffer.writeintbe (buffer.js:919:5)     @ object.<anonymous> (/home/liuzeya/http/examples/buffer.js:2:3)     @ module._compile (module.js:434:26)     @ object.module._extensions..js (module.js:452:10)     @ module.load (module.js:355:32)     @ function.module._load (module.js:310:12)     @ function.module.runmain (module.js:475:10)     @ startup (node.js:117:18)     @ node.js:951:3

help me understanding difference, please.

this can solved examining source at:

https://github.com/nodejs/node/blob/0a329d2d1f6bce2410d65ecd47175b5a4e1c1c91/lib/buffer.js

we can see call checkint: 

checkint(this,          value,          offset,          bytelength,          math.pow(2, 8 * bytelength - 1) - 1,          -math.pow(2, 8 * bytelength - 1));

working out math.pow's, see min -128 , max 127. if evaluate 0xff alone in console, see positive 255, out of range.

so hexadecimal constants positive. i'm sure can find in javascript standard. whereas, you're using signed version of call. can have explicit negative hexadecimal values in javascript, looks freaking odd in opinion, -0x1 in case.


Comments

Post a Comment

Popular posts from this blog

html - Outlook 2010 Anchor (url/address/link) -

i'm trying link specific pdf page msoutlook'10 or msword'10, #page=... anchor particularly useful , works fine elsewhere. unfortunately when click [ctr-k] in outlook or winword, links re-formatted assuming unc path. pdf file located on shared drive. using "file:" prefix links open pdf in adobe reader (outside of browser), , "http:" open inside browser. issue seem need open in browser "file:" prefix in order anchor work. know anchors work inside browser. outlook uses windows/explorer default program (based on file extension) seems open in adobe reader neglecting anchor. is aware of solution, link specific page or bookmark of shared-pdf ms outlook and/or winword link? common references: mailermailer.com/...anchor-tags-html-emails campaignmonitor.com/...anchor-links-in-email-newsletters/ stackoverflow.com/...anchor-in-pdf-document
Read more

javascript - Why does running this loop 9 times take 100x longer than running it 8 times? -

consider code: test = function() { } t = new test(); (var = 0; < 8; i++) { result = t instanceof test; } if change number of iterations 8 9 , loop take 100 times longer complete in latest version of firefox (41.0.1). tested on 2 different pcs , magic limit 8. here jsperf test used: http://jsperf.com/instanceof-8-times-vs-9-times does have idea why might happen? seems specific instanceof . not happen if else object, example check property. note: filed bugzilla bug this. jan de mooij mozilla team has posted details in bugzilla thread . here's simplistic interpretation of highly technical answers: in i < 8 case, firefox smart enough hoist result = t instanceof test; statement out of loop (according tests, doesn't seem omit altogether). in i < 9 case, apparently doesn't optimization . why? reason not clear, related fact 9 iterations threshold above function considered "hot" enough run through jit compiler. i < 8 cas...
Read more

Getting gateway time-out Rails app with Nginx + Puma running on Digital Ocean -

following this guide setup app on digital ocean droplet, not working. site not loading , it's throwing: "gateway time-out". the puma server works, since ps aux | grep puma prints: root 15878 0.0 0.4 376832 2168 ? sl 12:50 0:00 puma 2.13.4 (unix:///var/www/myapp/shared/tmp/sockets/myapp-puma.sock) [20150930164940] root 15881 0.0 0.7 903676 3692 ? sl 12:50 0:06 puma: cluster worker 0: 15878 [20150930164940] root 24654 0.0 0.1 11748 916 pts/2 s+ 18:00 0:00 grep --color=auto puma my nginx config: user root; worker_processes 1; events { worker_connections 1024; } http { upstream puma { server unix:///var/www/myapp/shared/tmp/sockets/myapp-puma.sock; } server { listen 80; server_name myapp.com; root /var/www/myapp/current/public; access_log /var/www/myapp/current/log/access.log; error_log /...
Read more