Core: Use Array.prototype.flat where supported

Calling `Array.prototype.concat.apply( [], inputArray )` to flatten `inputArray`
crashes for large arrays; using `Array.prototype.flat` avoids these issues in
browsers that support it. In case it's necessary to support these large arrays
even in older browsers, a polyfill for `Array.prototype.flat` can be loaded.
This is already being done by many applications.

Fixes gh-4320
Closes gh-4459

diff --git a/src/core.js b/src/core.js
index 0999da9f563ef5a67469625d52f2ef319cb2f5f3..af5d44214494e13aa0dc91aa887849bff7ae15d8 100644 (file)
--- a/src/core.js
+++ b/src/core.js
@@ -6,7 +6,7 @@ define( [
        "./var/arr",
        "./var/getProto",
        "./var/slice",
-       "./var/concat",
+       "./var/flat",
        "./var/push",
        "./var/indexOf",
        "./var/class2type",
@@ -18,7 +18,7 @@ define( [
        "./var/isWindow",
        "./core/DOMEval",
        "./core/toType"
-], function( arr, getProto, slice, concat, push, indexOf,
+], function( arr, getProto, slice, flat, push, indexOf,
        class2type, toString, hasOwn, fnToString, ObjectFunctionString,
        support, isWindow, DOMEval, toType ) {
 
@@ -397,7 +397,7 @@ jQuery.extend( {
                }
 
                // Flatten any nested arrays
-               return concat.apply( [], ret );
+               return flat( ret );
        },
 
        // A global GUID counter for objects

diff --git a/src/manipulation.js b/src/manipulation.js
index fc4c659fd74258537f2067d1200942778897b618..11bd5b07985aefa81cbd1e23fc402e6742235117 100644 (file)
--- a/src/manipulation.js
+++ b/src/manipulation.js
@@ -1,7 +1,7 @@
 define( [
        "./core",
        "./core/isAttached",
-       "./var/concat",
+       "./var/flat",
        "./var/isIE",
        "./var/push",
        "./core/access",
@@ -22,7 +22,7 @@ define( [
        "./traversing",
        "./selector",
        "./event"
-], function( jQuery, isAttached, concat, isIE, push, access, rtagName,
+], function( jQuery, isAttached, flat, isIE, push, access, rtagName,
        rscriptType, wrapMap, getAll, setGlobalEval, buildFragment,
        dataPriv, dataUser, acceptData, DOMEval, nodeName ) {
 
@@ -103,7 +103,7 @@ function cloneCopyEvent( src, dest ) {
 function domManip( collection, args, callback, ignored ) {
 
        // Flatten any nested arrays
-       args = concat.apply( [], args );
+       args = flat( args );
 
        var fragment, first, scripts, hasScripts, node, doc,
                i = 0,

diff --git a/src/var/concat.js b/src/var/concat.js
deleted file mode 100644 (file)
index e47c19d..0000000
--- a/src/var/concat.js
+++ /dev/null
@@ -1,7 +0,0 @@
-define( [
-       "./arr"
-], function( arr ) {
-       "use strict";
-
-       return arr.concat;
-} );

diff --git a/src/var/flat.js b/src/var/flat.js
new file mode 100644 (file)
index 0000000..6c7a271
--- /dev/null
+++ b/src/var/flat.js
@@ -0,0 +1,15 @@
+define( [
+       "./arr"
+], function( arr ) {
+
+"use strict";
+
+// Support: IE 11+, Edge 18+
+// Provide fallback for browsers without Array#flat.
+return arr.flat ? function( array ) {
+       return arr.flat.call( array );
+} : function( array ) {
+       return arr.concat.apply( [], array );
+};
+
+} );

diff --git a/test/unit/core.js b/test/unit/core.js
index be09163acf28c8ba6814b5291081d9758d2d544d..bc5d2fc258e231d45225967ec0cc4421a0a0cf9a 100644 (file)
--- a/test/unit/core.js
+++ b/test/unit/core.js
@@ -681,7 +681,7 @@ QUnit.test( "map()", function( assert ) {
 } );
 
 QUnit.test( "jQuery.map", function( assert ) {
-       assert.expect( 25 );
+       assert.expect( 28 );
 
        var i, label, result, callback;
 
@@ -781,6 +781,23 @@ QUnit.test( "jQuery.map", function( assert ) {
                return k % 2 ? k : [ k, k, k ];
        } );
        assert.equal( result.join( "" ), "00012223", "Array results flattened (#2616)" );
+
+       result = jQuery.map( [ [ [ 1, 2 ], 3 ], 4 ], function( v, k ) {
+               return v;
+       } );
+       assert.equal( result.length, 3, "Array flatten only one level down" );
+       assert.ok( Array.isArray( result[ 0 ] ), "Array flatten only one level down" );
+
+       // Support: IE 11+, Edge 18+
+       // Skip the test in browsers without Array#flat.
+       if ( Array.prototype.flat ) {
+               result = jQuery.map( Array( 300000 ), function( v, k ) {
+                       return k;
+               } );
+               assert.equal( result.length, 300000, "Able to map 300000 records without any problems (#4320)" );
+       } else {
+               assert.ok( "skip", "Array#flat doesn't supported on all browsers" );
+       }
 } );
 
 QUnit.test( "jQuery.merge()", function( assert ) {