Created
August 22, 2017 13:42
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Function that recursively flattens an array in vanilla JS with tests
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function recursivelyFlatten(array) { | |
if (!array) { | |
return [] | |
} | |
var result = []; | |
if (Array.isArray(array)) { | |
array.forEach((value) => { | |
result = result.concat(recursivelyFlatten(value)); | |
}); | |
} else { | |
result = [array]; | |
} | |
return result | |
} | |
function runTest(input, output, message) { | |
var expected = JSON.stringify(output); | |
var actual = JSON.stringify(recursivelyFlatten(input)); | |
if ( actual !== expected) { | |
throw message + ' expected: ' + expected + ', got: ' + actual; | |
} | |
console.log(message, '✔'); | |
} | |
const testSuit = { | |
withEmptyArray: () => runTest([], [], 'should return empty array if array is empty'), | |
zeroLevelsDeep: () => runTest([1,2,3], [1,2,3], 'should flatten array zero levels deep'), | |
multipleLevelsDeep: () => runTest([[1,2,[3]],4], [1,2,3,4], 'should flatten array multple levels deep'), | |
ignoreEmptyArrays: () => runTest([[], [1,2], [3, []], 4], [1,2,3,4], 'should ignore empty arrays') | |
} | |
Object.keys(testSuit).forEach((test) => testSuit[test]()); |
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