如何导入单个Lodash功能？ [英] How to Import a Single Lodash Function?

问题描述

使用webpack，我正在尝试导入 isEqual ，因为 lodash 似乎正在导入所有内容。我尝试过以下操作但没有成功：

Using webpack, I'm trying to import isEqual since lodash seems to be importing everything. I've tried doing the following with no success:

import { isEqual } from 'lodash'

import isEqual from 'lodash/lang'

import isEqual from 'lodash/lang/isEqual'

import { isEqual } from 'lodash/lang'

import { isEqual } from 'lodash/lang'

推荐答案

您可以将 lodash.isequal 作为单个模块安装，而不安装整个 lodash 包，如下所示：

You can install lodash.isequal as a single module without installing the whole lodash package like so:

npm install --save lodash.isequal

使用ECMAScript 5和CommonJS模块时，然后像这样导入：

When using ECMAScript 5 and CommonJS modules, you then import it like this:

var isEqual = require('lodash.isequal');

使用ES6模块，这将是：

Using ES6 modules, this would be:

import isEqual from 'lodash.isequal';

您可以在代码中使用它：

And you can use it in your code:

const obj1 = {username: 'peter'};
const obj2 = {username: 'peter'};
const obj3 = {username: 'gregory'};

isEqual(obj1, obj2) // returns true
isEqual(obj1, obj3) // returns false

资料来源： Lodash文件

导入后，您可以在代码中使用 isEqual 函数。请注意，如果您以这种方式导入它，它不是名为 _ 的对象的一部分，因此您
不引用它使用 _。isEqual ，但直接使用 isEqual 。

After importing, you can use the isEqual function in your code. Note that it is not a part of an object named _ if you import it this way, so you don't reference it with _.isEqual, but directly with isEqual.

替代方案：使用 lodash-es

Alternative: Using lodash-es

正如@kimamula ：

使用webpack 4和 lodash-es 4.17.7及更高版本，此代码有效。

With webpack 4 and lodash-es 4.17.7 and higher, this code works.

import { isEqual } from 'lodash-es';

这是因为webpack 4支持 sideEffects flag和 lodash-es 4.17.7及更高版本包括标志（设置为 false ）。

This is because webpack 4 supports the sideEffects flag and lodash-es 4.17.7 and higher includes the flag (which is set to false).

为什么不使用带斜线的版本？
此问题的其他答案表明您也可以使用短划线而不是点，如下所示：

Why Not Use the Version With the Slash? Other answers to this question suggest that you can also use a dash instead of a dot, like so:

import isEqual from 'lodash/isequal';

这也有效，但有两个小缺点：

This works, too, but there are two minor drawbacks:

• 你必须安装整个 lodash 包（ npm install --save lodash ），不只是小的单独的 lodash.isequal 包;存储空间很便宜且CPU很快，所以你可能不在乎这个


• 使用像webpack这样的工具时产生的捆绑包会稍微大些;我发现使用最小代码示例 isEqual 的捆绑包大小平均大28％（尝试过webpack 2和webpack 3，有或没有Babel，有或没有Uglify）

• You have to install the whole lodash package (npm install --save lodash), not just the small separate lodash.isequal package; storage space is cheap and CPUs are fast, so you may not care about this
• The resulting bundle when using tools like webpack will be slightly bigger; I found out that bundle sizes with a minimal code example of isEqual are on average 28% bigger (tried webpack 2 and webpack 3, with or without Babel, with or without Uglify)

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