lib: use destructuring for some constants

This change is to unify the declaration for constants into using
destructuring on the top-level-module scope, reducing some redundant
code.

PR-URL: #16063
Backport-PR-URL: #16494
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>

Author: starkwang

lib/_http_agent.js

@@ -25,8 +25,8 @@ const net = require('net');
 const util = require('util');
 const EventEmitter = require('events');
 const debug = util.debuglog('http');
-const async_id_symbol = process.binding('async_wrap').async_id_symbol;
-const nextTick = require('internal/process/next_tick').nextTick;
+const { async_id_symbol } = process.binding('async_wrap');
+const { nextTick } = require('internal/process/next_tick');
 
 // New Agent code.
 

lib/_http_client.js

@@ -24,19 +24,21 @@
 const util = require('util');
 const net = require('net');
 const url = require('url');
-const HTTPParser = process.binding('http_parser').HTTPParser;
+const { HTTPParser } = process.binding('http_parser');
 const assert = require('assert').ok;
-const common = require('_http_common');
-const httpSocketSetup = common.httpSocketSetup;
-const parsers = common.parsers;
-const freeParser = common.freeParser;
-const debug = common.debug;
-const OutgoingMessage = require('_http_outgoing').OutgoingMessage;
+const {
+  _checkIsHttpToken: checkIsHttpToken,
+  debug,
+  freeParser,
+  httpSocketSetup,
+  parsers
+} = require('_http_common');
+const { OutgoingMessage } = require('_http_outgoing');
 const Agent = require('_http_agent');
-const Buffer = require('buffer').Buffer;
+const { Buffer } = require('buffer');
 const { urlToOptions, searchParamsSymbol } = require('internal/url');
-const outHeadersKey = require('internal/http').outHeadersKey;
-const nextTick = require('internal/process/next_tick').nextTick;
+const { outHeadersKey } = require('internal/http');
+const { nextTick } = require('internal/process/next_tick');
 
 // The actual list of disallowed characters in regexp form is more like:
 //    /[^A-Za-z0-9\-._~!$&'()*+,;=/:@]/
@@ -149,7 +151,7 @@ function ClientRequest(options, cb) {
   }
 
   if (methodIsString && method) {
-    if (!common._checkIsHttpToken(method)) {
+    if (!checkIsHttpToken(method)) {
       throw new TypeError('Method must be a valid HTTP token');
     }
     method = this.method = method.toUpperCase();

lib/_http_common.js

@@ -22,16 +22,17 @@
 'use strict';
 
 const binding = process.binding('http_parser');
-const methods = binding.methods;
-const HTTPParser = binding.HTTPParser;
+const { methods, HTTPParser } = binding;
 
 const FreeList = require('internal/freelist');
-const ondrain = require('internal/http').ondrain;
+const { ondrain } = require('internal/http');
 const incoming = require('_http_incoming');
-const emitDestroy = require('async_hooks').emitDestroy;
-const IncomingMessage = incoming.IncomingMessage;
-const readStart = incoming.readStart;
-const readStop = incoming.readStop;
+const { emitDestroy } = require('async_hooks');
+const {
+  IncomingMessage,
+  readStart,
+  readStop
+} = incoming;
 
 const debug = require('util').debuglog('http');
 

lib/_http_outgoing.js

@@ -26,17 +26,16 @@ const Stream = require('stream');
 const util = require('util');
 const internalUtil = require('internal/util');
 const internalHttp = require('internal/http');
-const Buffer = require('buffer').Buffer;
+const { Buffer } = require('buffer');
 const common = require('_http_common');
 const checkIsHttpToken = common._checkIsHttpToken;
 const checkInvalidHeaderChar = common._checkInvalidHeaderChar;
-const outHeadersKey = require('internal/http').outHeadersKey;
-const async_id_symbol = process.binding('async_wrap').async_id_symbol;
-const nextTick = require('internal/process/next_tick').nextTick;
+const { outHeadersKey } = require('internal/http');
+const { async_id_symbol } = process.binding('async_wrap');
+const { nextTick } = require('internal/process/next_tick');
 
-const CRLF = common.CRLF;
-const debug = common.debug;
-const utcDate = internalHttp.utcDate;
+const { CRLF, debug } = common;
+const { utcDate } = internalHttp;
 
 var RE_FIELDS =
   /^(?:Connection|Transfer-Encoding|Content-Length|Date|Expect|Trailer|Upgrade)$/i;

lib/_http_server.js

@@ -23,17 +23,19 @@
 
 const util = require('util');
 const net = require('net');
-const HTTPParser = process.binding('http_parser').HTTPParser;
+const { HTTPParser } = process.binding('http_parser');
 const assert = require('assert').ok;
-const common = require('_http_common');
-const parsers = common.parsers;
-const freeParser = common.freeParser;
-const debug = common.debug;
-const CRLF = common.CRLF;
-const continueExpression = common.continueExpression;
-const chunkExpression = common.chunkExpression;
-const httpSocketSetup = common.httpSocketSetup;
-const OutgoingMessage = require('_http_outgoing').OutgoingMessage;
+const {
+  parsers,
+  freeParser,
+  debug,
+  CRLF,
+  continueExpression,
+  chunkExpression,
+  httpSocketSetup,
+  _checkInvalidHeaderChar: checkInvalidHeaderChar
+} = require('_http_common');
+const { OutgoingMessage } = require('_http_outgoing');
 const { outHeadersKey, ondrain } = require('internal/http');
 
 const STATUS_CODES = {
@@ -222,7 +224,7 @@ function writeHead(statusCode, reason, obj) {
     headers = obj;
   }
 
-  if (common._checkInvalidHeaderChar(this.statusMessage))
+  if (checkInvalidHeaderChar(this.statusMessage))
     throw new Error('Invalid character in statusMessage.');
 
   var statusLine = 'HTTP/1.1 ' + statusCode + ' ' + this.statusMessage + CRLF;

lib/_stream_readable.js

@@ -26,7 +26,7 @@ Readable.ReadableState = ReadableState;
 
 const EE = require('events');
 const Stream = require('stream');
-const Buffer = require('buffer').Buffer;
+const { Buffer } = require('buffer');
 const util = require('util');
 const debug = util.debuglog('stream');
 const BufferList = require('internal/streams/BufferList');

lib/_stream_wrap.js

@@ -2,11 +2,11 @@
 
 const assert = require('assert');
 const util = require('util');
-const Socket = require('net').Socket;
-const JSStream = process.binding('js_stream').JSStream;
 // TODO(bmeurer): Change this back to const once hole checks are
 // properly optimized away early in Ignition+TurboFan.
 var Buffer = require('buffer').Buffer;
+const { Socket } = require('net');
+const { JSStream } = process.binding('js_stream');
 const uv = process.binding('uv');
 const debug = util.debuglog('stream_wrap');
 

lib/_stream_writable.js

@@ -31,7 +31,7 @@ Writable.WritableState = WritableState;
 const util = require('util');
 const internalUtil = require('internal/util');
 const Stream = require('stream');
-const Buffer = require('buffer').Buffer;
+const { Buffer } = require('buffer');
 const destroyImpl = require('internal/streams/destroy');
 
 util.inherits(Writable, Stream);

lib/_tls_common.js

@@ -23,8 +23,7 @@
 
 const tls = require('tls');
 
-const SSL_OP_CIPHER_SERVER_PREFERENCE =
-    process.binding('constants').crypto.SSL_OP_CIPHER_SERVER_PREFERENCE;
+const { SSL_OP_CIPHER_SERVER_PREFERENCE } = process.binding('constants').crypto;
 
 // Lazily loaded
 var crypto = null;

lib/_tls_legacy.js

@@ -25,12 +25,12 @@ const internalUtil = require('internal/util');
 internalUtil.assertCrypto();
 
 const assert = require('assert');
-const Buffer = require('buffer').Buffer;
+const { Buffer } = require('buffer');
 const common = require('_tls_common');
-const Connection = process.binding('crypto').Connection;
+const { Connection } = process.binding('crypto');
 const EventEmitter = require('events');
 const stream = require('stream');
-const Timer = process.binding('timer_wrap').Timer;
+const { Timer } = process.binding('timer_wrap');
 const tls = require('tls');
 const util = require('util');