如何使用yarn将date-fns JS库导入Rails项目

Question

我尝试使用yarn将date-fns库导入到Rails项目中，但不起作用。

我使用yarn安装date-fns

yarn add date-fns

安装后，我尝试将这个库导入到app/javascript/packs/application.js文件中，但没有成功：

// This file is automatically compiled by Webpack, along with any other files
// present in this directory. You're encouraged to place your actual application logic in
// a relevant structure within app/javascript and only use these pack files to reference
// that code so it'll be compiled.
//

import 'core-js/stable';
import 'regenerator-runtime/runtime';
import format from "date-fns/format";

我得到一个错误：

> format(new Date(2014, 1, 11), 'yyyy-MM-dd')
> VM498:1 Uncaught ReferenceError: format is not defined
    at <anonymous>:1:1

如果我尝试使用app/assets/javascripts/application.js文件导入它：

//= require jquery3
//= require jquery_ujs
//= require popper
//= require bootstrap
//= require date-fns/format

console.log("date-fns", format(new Date(2014, 1, 11), "yyyy-MM-dd"));

看起来库是连接的，所以我可以调用方法format，但我得到了另一个错误：

> Uncaught ReferenceError: exports is not defined
# refers to this line 
>  Object.defineProperty(exports, "__esModule", {
>   value: true
>  });
> exports.default = format;

# and 

> Uncaught TypeError: Cannot read property 'default' of undefined
# refers to this line 
> function format(dirtyDate, dirtyFormatStr, dirtyOptions) {
>  (0, _index10.default)(2, arguments);

我做错了什么？

Answer 1

在Webpack和Rails中导入库的方法是通过yarn安装它，就像您所做的那样，然后将其要求到应用程序包中。

# console
$ yarn add date-fns

# app/javascript/packs/application.js
require("date-fns")