小编Ric*_*ego的帖子

我有一个 CollectionView，其中所有单元格都与视图中心对齐，利用自定义流布局。这是collectionViewController的代码：

let columnLayout = FlowLayout(
        minimumInteritemSpacing: 10,
        minimumLineSpacing: 10,
        sectionInset: UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)
    )
    
    
    var dataSource: [String] = ["USA", "Brazil", "China","Really long long long", "Unite Kingdom", "Japan", "Mexico", "India",  "Really long long", "Short", "USA", "Brazil", "China","Really long long long", "Unite Kingdom", "Japan", "Mexico", "India",  "Really long long"]
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        
        
        collectionView.collectionViewLayout = columnLayout
        collectionView.contentInsetAdjustmentBehavior = .always
        collectionView.register(TestCell.self, forCellWithReuseIdentifier: "Cell")
        collectionView.dragInteractionEnabled = true
        collectionView.dragDelegate = self
        collectionView.dropDelegate = self
        collectionView.delegate = self
        collectionView.dataSource …

我正在尝试使用以下代码从网页获取所有按钮元素：

const test = await page.evaluate(() => {
        return document.querySelectorAll("button")
})

console.log(test)

当我记录测试变量时，它会生成“未定义”，而当我在 chrome 控制台上运行以下代码时：

document.querySelectorAll("button")

它产生正确数量的元素。