Question

好的，我有一个元素设置来接收文件丢弃事件，但当我查看event.dataTransfer时，它是空白的。我还没有开始学习拖放式HTML5 API，但仍然有点模糊。我正在my site处理它。如果您不介意在我的代码中查看并查看正在进行的操作，那么我们将非常感激。正在记录整个event对象。

Answer 1

它工作正常，这只是控制台的一个错误。

function onDrop(event) {
    event.preventDefault();
    console.log(event.dataTransfer.files[0]);
}

Answer 2

另请查看此错误/行为：HTML5 drop event doesn't work unless dragover is handled

基本上，您需要处理悬停/拖动并指定dropEffect

Answer 3

我在以下位置找到了所需的东西

// We are trying to get our pickers to sync their provided type when you pull to refresh. But the implementation of refresh(:, completion:) that we added doesn’t get called.

import Foundation

protocol PickerItemProvider: class {
    associatedtype PickerType
    func findItem(by identifier: NSNumber) -> PickerType?
    func itemAt(_ indexPath: IndexPath) -> PickerType?
    func refresh(_ sender: Any, completion: (() -> Void)?)
}

extension PickerItemProvider {
    func findItem(by identifier: NSNumber) -> PickerType? {
        return nil
    }

    public func refresh(_ sender: Any, completion: (() -> Void)?) {
        print("the default refresh implementation")
    }
}

public class PickerSectionProvider<ProvidedType: Equatable> : PickerItemProvider {
    func itemAt(_ indexPath: IndexPath) -> ProvidedType? {
        return nil
    }
}

extension PickerItemProvider where PickerType: Equatable & SyncableEntity {
    func refresh(_ sender: Any, completion: (() -> Void)?) {
        print("we’re trying to have this implementation called instead of the above implementation of refresh")
        PickerType.startSync()
    }
}

protocol SyncableEntity {
    static func startSync()
}

extension SyncableEntity {
    static func startSync() {

    }
}

class ObservationType: Equatable, SyncableEntity {

}

func ==(lhs: ObservationType, rhs: ObservationType) -> Bool {
    return false
}

class GenericPickerViewController<PickerType: Equatable, ItemProvider: PickerItemProvider> where ItemProvider.PickerType == PickerType {
    var itemProvider: ItemProvider?

    init() {

    }

    func foo() {
        // Why doesn’t the implementation of refresh(:,completion:) we added get called here?
        itemProvider?.refresh("dummy sender") {

        }
    }
}

class PopupPickerRow<T: Equatable, ItemProvider: PickerItemProvider> where ItemProvider.PickerType == T {
    var pickerController = GenericPickerViewController<T, ItemProvider>()
}

let pickerSectionProvider = PickerSectionProvider<ObservationType>()

let row = PopupPickerRow<ObservationType, PickerSectionProvider<ObservationType>>()

row.pickerController.itemProvider = pickerSectionProvider

row.pickerController.foo()

Answer 4

关于 Esailja 的回答还有一件事，我正在从垃圾箱传输文件，当我从本地目录尝试时，它工作正常。

当ondrop被触发时，event.dataTransfer.files为空？

4 个答案: