如何在一定条件下将对象添加到数组? [英] How can I add object to array by certain condition?

问题描述

我这样尝试:

<script type="text/javascript">
    var clubs = [ 
        {id: 1, name : 'chelsea'},
        {id: 2, name : 'city'},
        {id: 3, name : 'liverpool'}
    ];
    var newClub = {id: 4, name: 'manchester united'}
    for(var i=0; i<clubs.length; i++) {
        if(clubs[i].id!=newClub.id) {
            clubs.push(newClub);
            break;
        }
    }
    console.log(clubs);
</script>

我想添加条件.如果clubs数组中不存在newClub对象的id，那么我想将该对象添加到数组中

I want to add condition. If id of newClub object is not exist in the clubs array, then I want to add the object to the array

有效

但是我问.那是最好的方法吗?还是还有另一种更好的方法?

But I ask. Is that the best way? Or is there another better way?

推荐答案

有效

不，不是. :-)如果第一条目不匹配，则您正在推动新俱乐部:

No, it doesn't. :-) You're pushing the new club if the first entry isn't a match:

var clubs = [ 
    {id: 1, name : 'chelsea'},
    {id: 2, name : 'city'},
    {id: 3, name : 'liverpool'}
];
function pushClub(newClub) {
  for(var i=0; i<clubs.length; i++) {
      if(clubs[i].id!=newClub.id) {
          clubs.push(newClub);
          break;
      }
  }
}
var newClub = {id: 4, name: 'manchester united'}
pushClub(newClub);
pushClub(newClub);
console.log(JSON.stringify(clubs));

.as-console-wrapper {
  max-height: 100% !important;
}

Note that there are two id = 4 clubs.

您需要遍历整个数组，然后才能知道是否应添加新项目.

You need to loop through the whole array before you know whether you should add the new item.

我可能会使用 ，查看该商品是否存在:

I'd probably use Array#some to see whether the item was present:

if (!clubs.some(c => c.id == newClub.id)) {
    clubs.push(newClub);
}

var clubs = [ 
    {id: 1, name : 'chelsea'},
    {id: 2, name : 'city'},
    {id: 3, name : 'liverpool'}
];
function pushClub(newClub) {
  if (!clubs.some(c => c.id == newClub.id)) {
    clubs.push(newClub);
  }
}
var newClub = {id: 4, name: 'manchester united'}
pushClub(newClub);
pushClub(newClub);
console.log(JSON.stringify(clubs));

.as-console-wrapper {
  max-height: 100% !important;
}

Note that there is only one id = 4 club.

我在这里使用ES2015 +箭头功能，但是您可以使用ES5传统功能:

I'm using an ES2015+ arrow function there, but you could use an ES5 traditional function:

if (!clubs.some(function(c) { return c.id == newClub.id; })) {
    clubs.push(newClub);
}

循环位于some中，如果回调曾经返回真实值，则返回true，否则返回false. (当回调函数返回真实值时，它也会提前停止.)

The loop is in some, which returns true if the callback ever returns a truthy value, or false if it never does. (It also stops early when the callback returns a truthy value.)

如果您想更新现有俱乐部(如果存在)，我会使用

If you wanted to update the existing club if present, I'd use Array#find instead:

var existingClub = clubs.find(c => c.id == newClub.id);
if (existingClub) {
    existingClub.name = newClub.name;
} else {
    clubs.push(newClub);
}

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