remove array-flatten dependency, no longer necessary

replaced array-flatten dependency with the new flat() method from JavaScript, which is supported in Node.js version 11.0.0 and above. This simplifies the code and reduces the number of dependencies

Author: benjaminPla

lib/application.js

@@ -25,7 +25,6 @@ var compileETag = require('./utils').compileETag;
 var compileQueryParser = require('./utils').compileQueryParser;
 var compileTrust = require('./utils').compileTrust;
 var deprecate = require('depd')('express');
-var flatten = require('array-flatten');
 var merge = require('utils-merge');
 var resolve = require('path').resolve;
 var setPrototypeOf = require('setprototypeof')
@@ -211,7 +210,7 @@ app.use = function use(fn) {
     }
   }
 
-  var fns = flatten(slice.call(arguments, offset));
+  var fns = slice.call(arguments, offset).flat()
 
   if (fns.length === 0) {
     throw new TypeError('app.use() requires a middleware function')

lib/router/index.js

@@ -19,7 +19,6 @@ var methods = require('methods');
 var mixin = require('utils-merge');
 var debug = require('debug')('express:router');
 var deprecate = require('depd')('express');
-var flatten = require('array-flatten');
 var parseUrl = require('parseurl');
 var setPrototypeOf = require('setprototypeof')
 
@@ -456,7 +455,7 @@ proto.use = function use(fn) {
     }
   }
 
-  var callbacks = flatten(slice.call(arguments, offset));
+  var callbacks = slice.call(arguments, offset).flat();
 
   if (callbacks.length === 0) {
     throw new TypeError('Router.use() requires a middleware function')

lib/router/route.js

@@ -14,7 +14,6 @@
  */
 
 var debug = require('debug')('express:router:route');
-var flatten = require('array-flatten');
 var Layer = require('./layer');
 var methods = require('methods');
 
@@ -182,7 +181,7 @@ Route.prototype.dispatch = function dispatch(req, res, done) {
  */
 
 Route.prototype.all = function all() {
-  var handles = flatten(slice.call(arguments));
+  var handles = slice.call(arguments).flat();
 
   for (var i = 0; i < handles.length; i++) {
     var handle = handles[i];
@@ -205,7 +204,7 @@ Route.prototype.all = function all() {
 
 methods.forEach(function(method){
   Route.prototype[method] = function(){
-    var handles = flatten(slice.call(arguments));
+    var handles = slice.call(arguments).flat();
 
     for (var i = 0; i < handles.length; i++) {
       var handle = handles[i];

lib/utils.js

@@ -16,7 +16,6 @@ var Buffer = require('safe-buffer').Buffer
 var contentDisposition = require('content-disposition');
 var contentType = require('content-type');
 var deprecate = require('depd')('express');
-var flatten = require('array-flatten');
 var mime = require('send').mime;
 var etag = require('etag');
 var proxyaddr = require('proxy-addr');
@@ -59,17 +58,6 @@ exports.isAbsolute = function(path){
   if ('\\\\' === path.substring(0, 2)) return true; // Microsoft Azure absolute path
 };
 
-/**
- * Flatten the given `arr`.
- *
- * @param {Array} arr
- * @return {Array}
- * @api private
- */
-
-exports.flatten = deprecate.function(flatten,
-  'utils.flatten: use array-flatten npm module instead');
-
 /**
  * Normalize the given `type`, for example "html" becomes "text/html".
  *

package.json

@@ -29,7 +29,6 @@
   ],
   "dependencies": {
     "accepts": "~1.3.8",
-    "array-flatten": "1.1.1",
     "body-parser": "1.20.2",
     "content-disposition": "0.5.4",
     "content-type": "~1.0.4",

test/utils.js

@@ -86,18 +86,3 @@ describe('utils.isAbsolute()', function(){
     assert(!utils.isAbsolute('foo/bar'));
   })
 })
-
-describe('utils.flatten(arr)', function(){
-  it('should flatten an array', function(){
-    var arr = ['one', ['two', ['three', 'four'], 'five']];
-    var flat = utils.flatten(arr)
-
-    assert.strictEqual(flat.length, 5)
-    assert.strictEqual(flat[0], 'one')
-    assert.strictEqual(flat[1], 'two')
-    assert.strictEqual(flat[2], 'three')
-    assert.strictEqual(flat[3], 'four')
-    assert.strictEqual(flat[4], 'five')
-    assert.ok(flat.every(function (v) { return typeof v === 'string' }))
-  })
-})