在javascript中从数组中过滤null [英] Filter null from an array in javascript

问题描述

我有一项任务是从给定数组中删除false，null，0，，undefined和NaN元素。我致力于解决除了null之外的所有解决方案。有谁能解释为什么？这是代码：

I have a task to remove false, null, 0, "", undefined, and NaN elements from an given array. I worked on a solution wich removes all except null. Anyone can explain why? Here's the code :

function bouncer(arr) {
var notAllowed = ["",false,null,0,undefined,NaN];
  for (i = 0; i < arr.length; i++){
      for (j=0; j<notAllowed.length;j++) {
         arr = arr.filter(function(val) {
               return val !== notAllowed[j];
              });
  }
 }
return arr;
}

bouncer([1,"", null, NaN, 2, undefined,4,5,6]);

推荐答案

好吧，因为你的所有价值都是假的，只是做一个 !! （强制转换为布尔值）检查：

Well, since all of your values are falsy, just do a !! (cast to boolean) check:

[1,"", null, NaN, 2, undefined,4,5,6].filter(x => !!x); //returns [1, 2, 4, 5, 6]

编辑：显然演员不是'需要：

Apparently the cast isn't needed:

[1,"", null, NaN, 2, undefined,4,5,6].filter(x => x);

上面的代码删除 null 就好了，这是 NaN 这就是问题所在。 Nina在她的回答中说， NaN！== NaN 。

And the code above removes null just fine, it's NaN that's the problem. NaN !== NaN as Nina says in her answer.

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