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Example to flat an nested array of integers in Javascript, using Jasmine.js as spec suite
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| class FlatAnything { | |
| flattenThis(collection){ | |
| if(itIsNotAnArrayAt(collection)) throw new Error('Only collections are allowed'); | |
| if(isAnEmpty(collection)) return []; | |
| const headOfCollection = headOf(collection); | |
| const tailOfCollection = tailOf(collection); | |
| if(itIsNotAnArrayAt(headOfCollection)) return theConcatenationOf([headOfCollection], this.flattenThis(tailOfCollection)); | |
| return theConcatenationOf(this.flattenThis(headOfCollection), this.flattenThis(tailOfCollection)); | |
| } | |
| } | |
| const headOf = ([head]) => head; | |
| const tailOf = ([, ...tail]) => tail; | |
| const isAnEmpty = (collection) => headOf(collection) === undefined && tailOf(collection).length == false; | |
| const itIsNotAnArrayAt = (thisElement) => Array.isArray(thisElement) == false; | |
| const theConcatenationOf = (thisElement, withThisElement) => thisElement.concat(withThisElement); | |
| module.exports = FlatAnything; |
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| describe('Flat Anything', function(){ | |
| var FlatAnything = require('../../../web/static/assets/js/flat_anything'); | |
| var flatAnything; | |
| beforeEach(function(){ | |
| flatAnything = new FlatAnything(); | |
| }); | |
| it('should not allow to receive anything but a collection', function() { | |
| expect(() => flatAnything.flattenThis(1)).toThrow(new Error("Only collections are allowed")); | |
| }); | |
| it('should transform [x] into [x]', function(){ | |
| expect(flatAnything.flattenThis([1])).toEqual([1]); | |
| }); | |
| it('should transform [x, y, z] into [x, y, z]', function(){ | |
| expect(flatAnything.flattenThis([1, 2, 3])).toEqual([1, 2, 3]); | |
| }); | |
| it('should transform [[x]] into [x]', function(){ | |
| var array = Array.from([[8,9]]); | |
| expect(flatAnything.flattenThis(array)).toEqual([8,9]); | |
| }); | |
| it('should transform [[x], y] into [x, y]', function(){ | |
| var array = [[1], 2]; | |
| expect(flatAnything.flattenThis(array)).toEqual([1,2]); | |
| }); | |
| it('should transform [[x], [y]] into [x, y]', function(){ | |
| const array = [[1], [2]]; | |
| expect(flatAnything.flattenThis(array)).toEqual([1,2]); | |
| }); | |
| it('should transform [[[x]], [y]] into [x, y]', function(){ | |
| const array = [[[1]], [2]]; | |
| expect(flatAnything.flattenThis(array)).toEqual([1,2]); | |
| }); | |
| it('should transform [[w, x,[y]], z] into [w, x, y, z] (Citrusbyte example)', function(){ | |
| const array = [[1,2,[3]], 4]; | |
| expect(flatAnything.flattenThis(array)).toEqual([1,2,3,4]); | |
| }); | |
| it('should transform [[[w, [x, y]]], [z]] into [w, x, y, z]', function(){ | |
| const array = [[[1,[2,3]]], [4]]; | |
| expect(flatAnything.flattenThis(array)).toEqual([1,2,3,4]); | |
| }); }); |
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