如何从JavaScript中的数组中删除虚假值

There are a lot of ways to remove elements from an array in JavaScript, but what’s the easiest way to remove all falsy values from an array? In order to answer that question we’ll take a close look at truthy versus falsy values and type coercion within the context of an algorithm scripting challenge.

有很多方法可以从JavaScript中删除数组中的元素，但是从数组中删除所有虚假值的最简单方法是什么？为了回答这个问题，我们将在算法脚本挑战的背景下仔细研究真值与假值以及类型强制。

算法指令 (Algorithm instructions)

Remove all falsy values from an array.

从数组中删除所有伪造的值。

Falsy values in JavaScript are false, null, 0, "", undefined, and NaN.

JavaScript中的false null false ， null ， 0 ， "" ， undefined和NaN 。

Hint: Try converting each value to a Boolean.

提示：尝试将每个值转换为布尔值。

提供的测试用例 (Provided Test Cases)

bouncer([7, "ate", "", false, 9])should return [7, "ate", 9].

bouncer([7, "ate", "", false, 9])应该返回[7, "ate", 9] 。
bouncer(["a", "b", "c"])should return ["a", "b", "c"].

bouncer(["a", "b", "c"])应该返回["a", "b", "c"] 。
bouncer([false, null, 0, NaN, undefined, ""])should return [].

bouncer([false, null, 0, NaN, undefined, ""])应该返回[] 。
bouncer([1, null, NaN, 2, undefined])should return [1, 2].

bouncer([1, null, NaN, 2, undefined])应该返回[1, 2] 。

解决方案1：.filter()和Boolean() (Solution 1: .filter( ) and Boolean( ))

PEDAC (PEDAC)

Understanding the Problem: We have one input, an array. Our goal is to remove all the falsy values from the array then return the array.

了解问题 ：我们只有一个输入，一个数组。我们的目标是从数组中删除所有伪造的值，然后返回数组。

The good people at freeCodeCamp have told us that falsy values in JavaScript are false, null, 0, "", undefined, and NaN.

freeCodeCamp的好人告诉我们，JavaScript中的false值是false ， null ， 0 ， "" ， undefined和NaN 。

They have also dropped a major hint for us! They suggest converting each value of the array into a boolean in order to accomplish this challenge. I think that’s a great hint!

他们也为我们提供了重要提示！他们建议将数组的每个值转换为布尔值以完成此挑战。我认为这是一个很好的提示！

Examples/Test Cases: Our provided test cases show us that if the input array only contains falsy values, then we should just return an empty array. That’s pretty straightforward.

示例/测试用例 ：我们提供的测试用例向我们展示了，如果输入数组仅包含伪造的值，那么我们应该只返回一个空数组。那很简单。

Data Structure: We are going to stick with arrays here.

数据结构 ：我们将在这里坚持使用数组。

Let’s talk about .filter():

让我们来谈谈.filter() ：

.filter() creates a new array with all elements that pass the test implemented by the provided function.

.filter()创建一个新数组，其中所有元素都通过了由提供的函数实现的测试。

In other words, .filter() goes through each element in an array and preserves all the elements that pass a certain test. All the elements in the array that fail that test are filtered out — they’re removed.

换句话说， .filter()遍历数组中的每个元素，并保留所有通过特定测试的元素。阵列中所有未通过测试的元素将被滤除-将其删除。

For example, if we had an array of numbers and we only wanted the numbers greater than 100, we could use .filter() to accomplish that:

例如，如果我们有一个数字数组，而只希望数字大于100，则可以使用.filter()来完成：

let numbers = [4, 56, 78, 99, 101, 150, 299, 300]numbers.filter(number => number > 100)// returns [ 101, 150, 299, 300 ]

Let’s talk about the hint of converting each element to a boolean. This is a good hint because we can use .filter() to return the array with only the truthy values.

让我们谈谈将每个元素转换为布尔值的提示。这是一个很好的提示，因为我们可以使用.filter()返回仅包含真值的数组。

We’re going to accomplish that through JavaScript type conversion.

我们将通过JavaScript类型转换来实现。

JavaScript gives us useful functions to convert one data type to another. String() converts to a string, Number() converts to a number, and Boolean() converts to a boolean.

JavaScript为我们提供了有用的功能，可以将一种数据类型转换为另一种数据类型。 String()转换为字符串， Number()转换为数字，而Boolean()转换为布尔值。

For example:

例如：

String(1234)// returns "1234"

Number("47")// returns 47

Boolean("meow")// returns true

Boolean() is the function we’ll be implementing with this challenge. If the argument provided to Boolean() is truthy, then Boolean() will return true. If the argument provided to Boolean() is falsy, then Boolean() will return false.

Boolean()是我们将在此挑战中实现的功能。如果提供给Boolean()的参数为true，则Boolean()将返回true. 如果提供给Boolean()的参数为falsy，则Boolean()将返回false 。

This is useful to us because we know from the instructions that only false, null, 0, "", undefined, and NaN are falsy in JavaScript. Every other value is truthy. Knowing that, if we convert each value in the input array to a boolean, we can remove all elements that evaluate to false, and that will satisfy the requirements for this challenge.

这对我们很有用，因为我们从指令中知道，在JavaScript中只有false ， null ， 0 ， "" ， undefined和NaN是虚假的。其他所有值都是真实的。知道了，如果我们将输入数组中的每个值转换为布尔值，则可以删除所有评估为false元素，这些元素将满足此挑战的要求。

Algorithm:

算法：

Determine which values in arr are falsy.

确定arr中的哪些值是虚假的。
Remove all falsy values.删除所有虚假值。
Return the new array that contains only truthy values.返回仅包含真实值的新数组。

Code: See below!

代码：见下文！

Without comments and removing the local variable:

没有注释并删除局部变量：

If you have other solutions and/or suggestions, please share in the comments!

如果您有其他解决方案和/或建议，请分享评论！

本文是freeCodeCamp算法脚本系列文章的一部分。 (This article is a part of the series freeCodeCamp Algorithm Scripting.)

本文引用了freeCodeCamp基本算法脚本：Falsy Bouncer 。 (This article references freeCodeCamp Basic Algorithm Scripting: Falsy Bouncer.)

You can follow me on Medium, LinkedIn, and GitHub!

您可以在Medium ， LinkedIn和GitHub上关注我！

翻译自: https://www.freecodecamp.org/news/how-to-remove-falsy-values-from-an-array-in-javascript-e623dbbd0ef2/