Question

我在javascript中有一个可观察的数组，

lookups.Data
[...]
    __proto__: []
    length: 2884
    [0]: {...}
    [1]: {...}
    [2]: {...}
    [3]: {...}
    [4]: {...}
    [5]: {...}
    [6]: {...}
    [7]: {...}
    [8]: {...}
    [9]: {...}
    [10]: {...}

每个记录都像，

lookups.Data[0]
{...}
    __proto__: {...}
    BookName: "Silapathikaram"
    Author: "Illangovadigal"
    type: "Tamil"

我有一个someBooks值的数组，

someBooks = ["ABC", "CED", "Silapathikaram"]

现在我需要从不在查找数据中的某些书中删除书籍。

如果是单个数组，单个项目我可以使用indexof like，

lookup.indexOf(book) == -1 // to check the existance of the book in the lookup

任何人都可以建议我有没有有效或简单的方法来做到这一点？任何帮助都会非常有用。

Answer 1

您可以在条件Array#filter功能中尝试Array#includes功能。

＆＃13;

const someBooks = ['A', 'B', 'C'];
const lookup = ['A', 'C'];

const filteredBooks = someBooks.filter(book => lookup.includes(book));

console.log(filteredBooks);

＆＃13;

Answer 2

最有效的方法是使用一套。构建一组所有书名，并找到名称和someBooks的交集。

let allNames = new Set(lookups.Data.map(e => e.BookName)),
    someBooks = new Set(["ABC", "CED", "Silapathikaram"]);

let intersection = new Set();
for (var elem of allNames) {
    if (someBooks.has(elem)) {
        intersection.add(elem);
    }
}

多次对整个书名列表执行.includes会很慢且效率低下，而使用一组不应该有这个问题，但最终还是取决于浏览器的实现。

Answer 3

为了过滤func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) { if(velocity.y>0) { //Code will work without the animation block.I am using animation block incase if you want to set any delay to it. UIView.animate(withDuration: 1.5, delay: 0, options: UIViewAnimationOptions(), animations: { self.searchBar.isHidden = true print("Hide") }, completion: nil) } else { UIView.animate(withDuration: 1.5, delay: 0, options: UIViewAnimationOptions(), animations: { self.searchBar.isHidden = false print("Unhide") }, completion: nil) } }数组中不存在的某些内容的值，您可以使用lookups.Data和some函数

filter

搜索查找数据中的元素数组

3 个答案: