--- id: ab306dbdcc907c7ddfc30830 challengeType: 5 forumTopicId: 16079 localeTitle: 扁平化 --- ## Description <section id='description'> 在这道题目中,我们需要写一个数组扁平化的函数。 如果你遇到了问题,请点击<a href='https://forum.freecodecamp.one/t/topic/157' target='_blank'>帮助</a>。 </section> ## Instructions <section id='instructions'> </section> ## Tests <section id='tests'> ```yml tests: - text: "<code>steamrollArray([[['a']], [['b']]])</code>应该返回<code>['a', 'b']</code>。" testString: assert.deepEqual(steamrollArray([[["a"]], [["b"]]]), ["a", "b"]); - text: <code>steamrollArray([1, [2], [3, [[4]]]])</code>应该返回<code>[1, 2, 3, 4]</code>。 testString: assert.deepEqual(steamrollArray([1, [2], [3, [[4]]]]), [1, 2, 3, 4]); - text: <code>steamrollArray([1, [], [3, [[4]]]])</code>应该返回<code>[1, 3, 4]</code>。 testString: assert.deepEqual(steamrollArray([1, [], [3, [[4]]]]), [1, 3, 4]); - text: <code>steamrollArray([1, {}, [3, [[4]]]])</code>应该返回<code>[1, {}, 3, 4]</code>。 testString: assert.deepEqual(steamrollArray([1, {}, [3, [[4]]]]), [1, {}, 3, 4]); ``` </section> ## Challenge Seed <section id='challengeSeed'> <div id='js-seed'> ```js function steamrollArray(arr) { // I'm a steamroller, baby return arr; } steamrollArray([1, [2], [3, [[4]]]]); ``` </div> </section> ## Solution <section id='solution'> ```js function steamrollArray(arr) { if (!Array.isArray(arr)) { return [arr]; } var out = []; arr.forEach(function(e) { steamrollArray(e).forEach(function(v) { out.push(v); }); }); return out; } ``` </section>