从对象中动态删除多个 key/value 对

Question

假设我有一组对象。有些keys/values我不想要。删除 one key/value 对的传统方法是这样使用 delete：

for (var i = 0; i < tracks.length; i++) {
  delete tracks[i]["currency"];
  ...
}

我拉入的对象可能有 30 多对。有没有一种方法可以说明我想要哪些对并删除所有其他对？因此，例如，在这个对象数组中，我只想保留 trackName、kind、price

var tracks = [{
    trackNumber: "01",
    trackName: "Track 1",
    trackDuration: "5:35",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "02",
    trackName: "Track 2",
    trackDuration: "5:15",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "03",
    trackName: "Track 3",
    trackDuration: "5:07",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "04",
    trackName: "Track 4",
    trackDuration: "0:16",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "05",
    trackName: "Track 5",
    trackDuration: "5:35",
    kind: "song",
    currency: "USD",
    price: 1.29
}];

Answer 1

您介意使用下划线“.pick(object, *keys) ”、“.omit(object, *keys) ”并将新对象推入新数组吗.

Answer 2

不确定这是否是您想要的，但它会遍历列表，并且 return 相同的列表，其中只有给定的键。 keys 是一个键数组。

function LimitArray(keys, list){
    var returnArr = [];
    for (var i in list){
       var row = {};
       for (key in list[i]){
          row[key] = list[i][key];
       }
       returnArr.push(row);
    }
    return returArr;
}

您也可以用其他几种方式编写此代码以修改原始列表，但我不确定这是否正是您想要的，所以我只是 return 编辑了一个新列表。

如果你想改变原来的，你可以这样做：

var select = ["a","b"]
list.map(function(val,index, array)
   {
   var keys = Object.keys(val);
   for (var key in keys){
      if(-1 == select.indexOf(keys[key]])  delete val[keys[key]];
   }}.bind(this));

我相信应该也是该做的事。它将遍历列表，并删除所有不在 select.

中的键

Answer 3

迭代数组并保留每个对象的所需内容。

var keep = ['trackName', 'kind', 'price'];

for(var i = 0;i < tracks.length; i++){

    for(var key in tracks[i]){
        if(keep.indexOf(key) === -1)delete tracks[i][key];
    }

}

Answer 4

一个自我描述的解决方案：

// what you want to keep:
var want_to_keep = ['trackName', 'kind', 'price'];

// loop trough every main element of tracks:
for (var i=0; i<tracks.length; i++)
    // now go trough every element of the current track:
    for (var key in tracks[i])
        // check if the current track key is wanted:
        if (want_to_keep.indexOf(key) < 0)
            delete tracks[i][el];

Answer 5

这是我的建议，因为我觉得它更优雅：

// create new array of objects from old one
var fixed = jQuery.map(tracks, function(element, index){
    return {"trackName": element.trackName, "kind": element.kind, "price": element.price};
}); 
// delete old array   
tracks = null;

Answer 6

我能想到的最简单的解决方案：

/**
 * Returns new collection which items contains only specified properties
 * @param {Array} collection of items
 * @param {Array} properties to keep
 */

function keepCollectionProperties(collection, properties) {
    return collection.map(function(item) {
        var newItem = {}
        for(var i = 0, prop; prop = properties[i]; i++)
            if (typeof item[prop] !== 'undefined')
                newItem[prop] = item[prop]
        return newItem
    })
}

var tracks = [{
    trackNumber: "01",
    trackName: "Track 1",
    trackDuration: "5:35",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "02",
    trackName: "Track 2",
    trackDuration: "5:15",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "03",
    trackName: "Track 3",
    trackDuration: "5:07",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "04",
    trackName: "Track 4",
    trackDuration: "0:16",
    kind: "song",
    currency: "USD",
    price: 1.29
}, {
    trackNumber: "05",
    trackName: "Track 5",
    trackDuration: "5:35",
    kind: "song",
    currency: "USD",
    price: 1.29
}];

var output = keepCollectionProperties(tracks, ['trackName', 'kind', 'price'])
document.write(JSON.stringify(output))

注意：避免使用delete，它会改变"shape"对象并损害性能。尽可能使用 item.prop = null。我的函数 returns new collection，所以没有必要，但是如果你打算再次填充新的 collection，最好将不需要的 props 设置为 null.

从对象中动态删除多个 key/value 对

Dynamically removing multiple key/value pairs from an object

javascript

arrays

json

object

key-value