javascript - 计算数组中的对象数，忽略 null

Question

这个问题已经有答案了:

Why is typeof null "object"? (10 个回答)

已关闭 5 年前。

我还很初级，如果不合适请见谅。

尝试计算数组中的对象数，忽略 null。这是我到目前为止的代码:

    function countTheObjects (arr) {

        let count = 0;

          for (let i = 0; i < arr.length; i++) {
             if (typeof arr[i] === 'object') {
               count++;
             }
             if (arr[i] === null) {
               count--;
             }


           }
         return count;
        }

我做错了什么？

编辑:

你们给我的所有这些代码都返回与我的错误完全相同的错误。这些是代码必须通过的测试:

describe('countTheObjects', function () {
  it('returns the count of objects inside an array of random data types', function () {
    expect(countTheObjects([])).to.equal(0);
    expect(countTheObjects([1, 3, 4, 5])).to.equal(0);
    expect(countTheObjects([1, 3, 4, 5, 'foo'])).to.equal(0);
    expect(countTheObjects([1, 3, 4, 5, {}, {}, {}, 'foo'])).to.equal(3);
    expect(countTheObjects([1, [], 3, 4, 5, {}, {}, {}, 'foo'])).to.equal(3);
    expect(countTheObjects([1, [], null, 3, 4, 5, {}, {}, {}, 'foo'])).to.equal(3);
    expect(countTheObjects([1, {}, [], null, null, 'foo', 3, 4, 5, {}, {}, {}, 'foo'])).to.equal(4);
  });
});

Answer 1

你的代码是错误的，因为typeof null ===“object”

function countTheObjects (arr) {
  let count = 0;
  
  arr.forEach(e => {
    if (typeof e === "object" && e !== null) {
      count++;
    }
  });
  
  return count;
}
    
    
alert(countTheObjects([
  1, 2, 3, null, null, 5, 6, null, {}, {}, {}
]));