use rest parameters instead of arguments

now possible by dropping support for node older than v6

.eslintrc.js

@@ -44,8 +44,6 @@ module.exports = {
     "valid-jsdoc": 0,
     "comma-dangle": 0,
     "arrow-parens": 0,
-    // Compat: support for rest params is behind a flag for node v5.x
-    "prefer-rest-params": 0,
   },
   "parserOptions": {
     "ecmaVersion": 6,

lighthouse-cli/test/global-mocha-hooks.js

@@ -15,11 +15,11 @@ Object.keys(assert)
   .filter(key => typeof assert[key] === 'function')
   .forEach(key => {
     const _origFn = assert[key];
-    assert[key] = function() {
+    assert[key] = function(...args) {
       if (currTest) {
         currTest._assertions++;
       }
-      return _origFn.apply(this, arguments);
+      return _origFn.apply(this, args);
     };
   }
 );

lighthouse-core/gather/driver.js

@@ -801,11 +801,9 @@ function captureJSCallUsage(funcRef, set) {
   const originalFunc = funcRef;
   const originalPrepareStackTrace = __nativeError.prepareStackTrace;
 
-  return function() {
+  return function(...args) {
     // Note: this function runs in the context of the page that is being audited.
 
-    const args = [...arguments]; // callee's arguments.
-
     // See v8's Stack Trace API https://github.com/v8/v8/wiki/Stack-Trace-API#customizing-stack-traces
     __nativeError.prepareStackTrace = function(error, structStackTrace) {
       // First frame is the function we injected (the one that just threw).
@@ -850,7 +848,7 @@ function captureJSCallUsage(funcRef, set) {
     __nativeError.prepareStackTrace = originalPrepareStackTrace;
 
     // eslint-disable-next-line no-invalid-this
-    return originalFunc.apply(this, arguments);
+    return originalFunc.apply(this, args);
   };
 }
 

lighthouse-core/lib/console-quieter.js

@@ -26,14 +26,14 @@ class ConsoleQuieter {
   static mute(opts) {
     ConsoleQuieter._logs = ConsoleQuieter._logs || [];
 
-    console.log = function() {
-      ConsoleQuieter._logs.push({type: 'log', args: arguments, prefix: opts.prefix});
+    console.log = function(...args) {
+      ConsoleQuieter._logs.push({type: 'log', args: args, prefix: opts.prefix});
     };
-    console.warn = function() {
-      ConsoleQuieter._logs.push({type: 'warn', args: arguments, prefix: opts.prefix});
+    console.warn = function(...args) {
+      ConsoleQuieter._logs.push({type: 'warn', args: args, prefix: opts.prefix});
     };
-    console.error = function() {
-      ConsoleQuieter._logs.push({type: 'error', args: arguments, prefix: opts.prefix});
+    console.error = function(...args) {
+      ConsoleQuieter._logs.push({type: 'error', args: args, prefix: opts.prefix});
     };
   }
 

lighthouse-core/lib/log.js

@@ -40,8 +40,9 @@ class Emitter extends EventEmitter {
    * Fires off all status updates. Listen with
    * `require('lib/log').events.addListener('status', callback)`
    * @param {string} title
+   * @param {...*} args
    */
-  issueStatus(title, args) {
+  issueStatus(title, ...args) {
     if (title === 'status' || title === 'statusEnd') {
       this.emit(title, args);
     }
@@ -50,8 +51,9 @@ class Emitter extends EventEmitter {
   /**
    * Fires off all warnings. Listen with
    * `require('lib/log').events.addListener('warning', callback)`
+   * @param {...*} args
    */
-  issueWarning(args) {
+  issueWarning(...args) {
     this.emit('warning', args);
   }
 }
@@ -113,23 +115,23 @@ class Log {
     Log._logToStdErr(`${prefix}:${level || ''}`, [data.method, snippet]);
   }
 
-  static log(title) {
-    Log.events.issueStatus(title, arguments);
-    return Log._logToStdErr(title, Array.from(arguments).slice(1));
+  static log(title, ...args) {
+    Log.events.issueStatus(title, ...args);
+    return Log._logToStdErr(title, args);
   }
 
-  static warn(title) {
-    Log.events.issueWarning(arguments);
-    return Log._logToStdErr(`${title}:warn`, Array.from(arguments).slice(1));
+  static warn(title, ...args) {
+    Log.events.issueWarning(title, ...args);
+    return Log._logToStdErr(`${title}:warn`, args);
   }
 
-  static error(title) {
-    return Log._logToStdErr(`${title}:error`, Array.from(arguments).slice(1));
+  static error(title, ...args) {
+    return Log._logToStdErr(`${title}:error`, args);
   }
 
-  static verbose(title) {
+  static verbose(title, ...args) {
     Log.events.issueStatus(title);
-    return Log._logToStdErr(`${title}:verbose`, Array.from(arguments).slice(1));
+    return Log._logToStdErr(`${title}:verbose`, args);
   }
 
   /**

lighthouse-core/report/report-generator.js

@@ -101,10 +101,10 @@ class ReportGenerator {
     });
 
     // arg1 && arg2 && ... && argn
-    Handlebars.registerHelper('and', function() {
+    Handlebars.registerHelper('and', function(...args) {
       let arg = false;
-      for (let i = 0, n = arguments.length - 1; i < n; i++) {
-        arg = arguments[i];
+      for (let i = 0, n = args.length - 1; i < n; i++) {
+        arg = args[i];
         if (!arg) {
           break;
         }

lighthouse-core/test/global-mocha-hooks.js

@@ -16,11 +16,11 @@ Object.keys(assert)
   .filter(key => typeof assert[key] === 'function')
   .forEach(key => {
     const _origFn = assert[key];
-    assert[key] = function() {
+    assert[key] = function(...args) {
       if (currTest) {
         currTest._assertions++;
       }
-      return _origFn.apply(this, arguments);
+      return _origFn.apply(this, args);
     };
   }
 );