举两个例子:

一个例子

// Remove from Listing the Items Checked in Checkbox for Delete
let temp_products_images = store.state.c_products.products_images
if (temp_products_images != null) {
    for (var l = temp_products_images.length; l--;) {
        // 'mark' is the checkbox field
        if (temp_products_images[l].mark == true) {
            store.state.c_products.products_images.splice(l,1);         // THIS WORKS
            // this.$delete(store.state.c_products.products_images,l);  // THIS ALSO WORKS
        }
    }
}

两个例子

// Remove from Listing the Items Checked in Checkbox for Delete
let temp_products_images = store.state.c_products.products_images
if (temp_products_images != null) {
    let l = temp_products_images.length
    while (l--)
    {
        // 'mark' is the checkbox field
        if (temp_products_images[l].mark == true) {
            store.state.c_products.products_images.splice(l,1);         // THIS WORKS
            // this.$delete(store.state.c_products.products_images,l);  // THIS ALSO WORKS
        }
    }
}

为什么在.splice上浪费CPU周期?该操作必须一次又一次地执行整个循环以删除数组中的一个元素。

为什么不只是在一个循环中使用传统的2个旗帜?

Const元素= [1,5,5,3,5,2,4]; Const remove = 5 I = 0 For(令j = 0;J < elements.length;j + +) { If(元素[j] !==删除){ 元素[i] =元素[j] 我+ + ｝ ｝ 元素。长度= I

这是这个简单线性时间问题的一个简单线性时间解。

当我运行这个代码片段时，n = 100万，每次调用filterInPlace()需要0.013到0.016秒。一个二次解(例如，公认的答案)将需要它的一百万倍左右。

// Remove from array every item such that !condition(item). function filterInPlace(array, condition) { var iOut = 0; for (var i = 0; i < array.length; i++) if (condition(array[i])) array[iOut++] = array[i]; array.length = iOut; } // Try it out. A quadratic solution would take a very long time. var n = 1*1000*1000; console.log("constructing array..."); var Auction = {auctions: []}; for (var i = 0; i < n; ++i) { Auction.auctions.push({seconds:1}); Auction.auctions.push({seconds:2}); Auction.auctions.push({seconds:0}); } console.log("array length should be "+(3*n)+": ", Auction.auctions.length) filterInPlace(Auction.auctions, function(auction) {return --auction.seconds >= 0; }) console.log("array length should be "+(2*n)+": ", Auction.auctions.length) filterInPlace(Auction.auctions, function(auction) {return --auction.seconds >= 0; }) console.log("array length should be "+n+": ", Auction.auctions.length) filterInPlace(Auction.auctions, function(auction) {return --auction.seconds >= 0; }) console.log("array length should be 0: ", Auction.auctions.length)

注意，这只是修改原始数组，而不是创建一个新数组;这样做是有好处的，例如，在数组是程序的单一内存瓶颈的情况下;在这种情况下，您不希望创建另一个相同大小的数组，即使是临时的。

删除参数

        oldJson=[{firstName:'s1',lastName:'v1'},
                 {firstName:'s2',lastName:'v2'},
                 {firstName:'s3',lastName:'v3'}]
        
        newJson = oldJson.map(({...ele}) => {
          delete ele.firstName;
          return ele;
          })

它删除和创建新的数组，因为我们在每个对象上使用展开运算符，所以原始数组对象也不会受到损害

普通的for循环对我来说更熟悉，我只需要在每次从数组中删除一个项时递减索引

//5个正确，5个错误 Var arr1 =[假，假，真，真，假，真，假，真，真，假]; //从数组中删除false For (var I = 0;I < arr1.length;我+ +){ If (arr1[i] === false){ arr1。拼接(我,1); I——;//如果item被移除，则递减索引 ｝ ｝ Console.log (arr1);//应该是5个true

当您执行.splice()时，数组正在重新索引，这意味着当一个索引被删除时，您将跳过一个索引，并且缓存的.length已过时。

要修复它，你要么需要在.splice()后面递减i，要么简单地反向迭代…

var i = Auction.auctions.length
while (i--) {
    ...
    if (...) { 
        Auction.auctions.splice(i, 1);
    } 
}

这样，重新索引就不会影响迭代中的下一项，因为索引只影响从当前点到数组末尾的项，并且迭代中的下一项低于当前点。