console: refactor to use rest params and template strings

Overall cleanup in code, eliminate reliance on `arguments`.

Benchmarks show that as of v8 5.0.71.32, using rest params + apply
has good performance. The spread operator is not yet well optimized
in v8

```
misc/console.js method=restAndSpread concat=1 n=1000000: 374779.38359
misc/console.js method=restAndSpread concat=0 n=1000000: 375988.30434
misc/console.js method=argumentsAndApply concat=1 n=1000000: 682618.61125
misc/console.js method=argumentsAndApply concat=0 n=1000000: 645093.74443
misc/console.js method=restAndApply concat=1 n=1000000: 682931.41217
misc/console.js method=restAndApply concat=0 n=1000000: 664473.09700
```

PR-URL: https://github.com/nodejs/node/pull/6233
Reviewed-By: Brian White <mscdex@mscdex.net>

1 files changed, 15 insertions, 16 deletions

diff --git a/lib/console.js b/lib/console.js
index 78c6955af5..646e268624 100644
--- a/lib/console.js
+++ b/lib/console.js
@@ -35,16 +35,20 @@ function Console(stdout, stderr) {
   }
 }
 
-Console.prototype.log = function() {
-  this._stdout.write(util.format.apply(null, arguments) + '\n');
+
+// As of v8 5.0.71.32, the combination of rest param, template string
+// and .apply(null, args) benchmarks consistently faster than using
+// the spread operator when calling util.format.
+Console.prototype.log = function(...args) {
+  this._stdout.write(`${util.format.apply(null, args)}\n`);
 };
 
 
 Console.prototype.info = Console.prototype.log;
 
 
-Console.prototype.warn = function() {
-  this._stderr.write(util.format.apply(null, arguments) + '\n');
+Console.prototype.warn = function(...args) {
+  this._stderr.write(`${util.format.apply(null, args)}\n`);
 };
 
 
@@ -52,9 +56,8 @@ Console.prototype.error = Console.prototype.warn;
 
 
 Console.prototype.dir = function(object, options) {
-  this._stdout.write(util.inspect(object, util._extend({
-    customInspect: false
-  }, options)) + '\n');
+  options = Object.assign({customInspect: false}, options);
+  this._stdout.write(`${util.inspect(object, options)}\n`);
 };
 
 
@@ -66,7 +69,7 @@ Console.prototype.time = function(label) {
 Console.prototype.timeEnd = function(label) {
   var time = this._times.get(label);
   if (!time) {
-    throw new Error('No such label: ' + label);
+    throw new Error(`No such label: ${label}`);
   }
   const duration = process.hrtime(time);
   const ms = duration[0] * 1000 + duration[1] / 1e6;
@@ -75,24 +78,20 @@ Console.prototype.timeEnd = function(label) {
 };
 
 
-Console.prototype.trace = function trace() {
+Console.prototype.trace = function trace(...args) {
   // TODO probably can to do this better with V8's debug object once that is
   // exposed.
   var err = new Error();
   err.name = 'Trace';
-  err.message = util.format.apply(null, arguments);
+  err.message = util.format.apply(null, args);
   Error.captureStackTrace(err, trace);
   this.error(err.stack);
 };
 
 
-Console.prototype.assert = function(expression) {
+Console.prototype.assert = function(expression, ...args) {
   if (!expression) {
-    const argsLen = arguments.length || 1;
-    const arr = new Array(argsLen - 1);
-    for (var i = 1; i < argsLen; i++)
-      arr[i - 1] = arguments[i];
-    require('assert').ok(false, util.format.apply(null, arr));
+    require('assert').ok(false, util.format.apply(null, args));
   }
 };