如何防止向 javascript 数组添加重复键 [英] how to prevent adding duplicate keys to a javascript array

问题描述

我发现了很多相关的问题，答案都是关于 for...in 循环和使用 hasOwnProperty 但我所做的一切都无法正常工作.我想要做的就是检查数组中是否存在某个键，如果不存在，则添加它.

I found a lot of related questions with answers talking about for...in loops and using hasOwnProperty but nothing I do works properly. All I want to do is check whether or not a key exists in an array and if not, add it.

我从一个空数组开始，然后在使用 jQuery 清理页面时添加键.

I start with an empty array then add keys as the page is scrubbed with jQuery.

最初，我希望像下面这样简单的东西会起作用:(使用通用名称)

Initially, I hoped that something simple like the following would work: (using generic names)

if (!array[key])
   array[key] = value;

不行.跟进:

for (var in array) {
   if (!array.hasOwnProperty(var))
      array[key] = value;
}

也试过了:

if (array.hasOwnProperty(key) == false)
   array[key] = value;

这些都没有奏效.要么没有任何东西被推送到数组中，要么我尝试做的事情并不比简单地声明 array[key] = value 更好，为什么这么简单的事情做起来这么难.有什么想法可以使这项工作发挥作用吗?

None of this has worked. Either nothing is pushed to the array or what I try is no better than simply declaring array[key] = value Why is something so simple so difficult to do. Any ideas to make this work?

推荐答案

一般来说，这最好用对象来完成，因为 JavaScript 并没有真正的关联数组:

Generally speaking, this is better accomplished with an object instead since JavaScript doesn't really have associative arrays:

var foo = { bar: 0 };

然后使用 in 检查密钥:

Then use in to check for a key:

if ( !( 'bar' in foo ) ) {
    foo['bar'] = 42;
}

正如在下面的评论中正确指出的那样，此方法仅在您的键是字符串或可以表示为字符串的项目(例如数字)时有用.

As was rightly pointed out in the comments below, this method is useful only when your keys will be strings, or items that can be represented as strings (such as numbers).

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