lib: use const to define constants

This commit replaces a number of var statements throughout
the lib code with const statements.

PR-URL: nodejs#541
Reviewed-By: Ben Noordhuis <[email protected]>

Author: cjihrig

lib/_debug_agent.js

@@ -1,17 +1,16 @@
 'use strict';
 
-var assert = require('assert');
-var net = require('net');
-var util = require('util');
-var Buffer = require('buffer').Buffer;
-
-var Transform = require('stream').Transform;
+const assert = require('assert');
+const net = require('net');
+const util = require('util');
+const Buffer = require('buffer').Buffer;
+const Transform = require('stream').Transform;
 
 exports.start = function start() {
   var agent = new Agent();
 
   // Do not let `agent.listen()` request listening from cluster master
-  var cluster = require('cluster');
+  const cluster = require('cluster');
   cluster.isWorker = false;
   cluster.isMaster = true;
 

lib/_debugger.js

@@ -1,14 +1,14 @@
 'use strict';
 
-var util = require('util'),
-    path = require('path'),
-    net = require('net'),
-    vm = require('vm'),
-    module = require('module'),
-    repl = module.requireRepl(),
-    inherits = util.inherits,
-    assert = require('assert'),
-    spawn = require('child_process').spawn;
+const util = require('util');
+const path = require('path');
+const net = require('net');
+const vm = require('vm');
+const module = require('module');
+const repl = module.requireRepl();
+const inherits = util.inherits;
+const assert = require('assert');
+const spawn = require('child_process').spawn;
 
 exports.start = function(argv, stdin, stdout) {
   argv || (argv = process.argv.slice(2));
@@ -137,7 +137,7 @@ Protocol.prototype.serialize = function(req) {
 };
 
 
-var NO_FRAME = -1;
+const NO_FRAME = -1;
 
 function Client() {
   net.Stream.call(this);
@@ -176,7 +176,7 @@ Client.prototype._addHandle = function(desc) {
 };
 
 
-var natives = process.binding('natives');
+const natives = process.binding('natives');
 
 
 Client.prototype._addScript = function(desc) {
@@ -645,7 +645,7 @@ Client.prototype.fullTrace = function(cb) {
 
 
 
-var commands = [
+const commands = [
   [
     'run (r)',
     'cont (c)',
@@ -772,22 +772,22 @@ function Interface(stdin, stdout, args) {
   process.once('SIGTERM', process.exit.bind(process, 0));
   process.once('SIGHUP', process.exit.bind(process, 0));
 
-  var proto = Interface.prototype,
-      ignored = ['pause', 'resume', 'exitRepl', 'handleBreak',
-                 'requireConnection', 'killChild', 'trySpawn',
-                 'controlEval', 'debugEval', 'print', 'childPrint',
-                 'clearline'],
-      shortcut = {
-        'run': 'r',
-        'cont': 'c',
-        'next': 'n',
-        'step': 's',
-        'out': 'o',
-        'backtrace': 'bt',
-        'setBreakpoint': 'sb',
-        'clearBreakpoint': 'cb',
-        'pause_': 'pause'
-      };
+  var proto = Interface.prototype;
+  const ignored = ['pause', 'resume', 'exitRepl', 'handleBreak',
+                   'requireConnection', 'killChild', 'trySpawn',
+                   'controlEval', 'debugEval', 'print', 'childPrint',
+                   'clearline'];
+  const shortcut = {
+    'run': 'r',
+    'cont': 'c',
+    'next': 'n',
+    'step': 's',
+    'out': 'o',
+    'backtrace': 'bt',
+    'setBreakpoint': 'sb',
+    'clearBreakpoint': 'cb',
+    'pause_': 'pause'
+  };
 
   function defineProperty(key, protoKey) {
     // Check arity