--- /dev/null
+'use strict';
+var $ = require('../internals/export');
+var flattenIntoArray = require('../internals/flatten-into-array');
+var toObject = require('../internals/to-object');
+var toLength = require('../internals/to-length');
+var toInteger = require('../internals/to-integer');
+var arraySpeciesCreate = require('../internals/array-species-create');
+
+// `Array.prototype.flat` method
+// https://github.com/tc39/proposal-flatMap
+$({ target: 'Array', proto: true }, {
+ flat: function flat(/* depthArg = 1 */) {
+ var depthArg = arguments.length ? arguments[0] : undefined;
+ var O = toObject(this);
+ var sourceLen = toLength(O.length);
+ var A = arraySpeciesCreate(O, 0);
+ A.length = flattenIntoArray(A, O, O, sourceLen, 0, depthArg === undefined ? 1 : toInteger(depthArg));
+ return A;
+ }
+});