Rails 5/6:如何在webpacker中包含JS函数? [英] Rails 5/6: How to include JS functions with webpacker?

问题描述

我正在尝试将Rails 3应用程序更新为Rails 6，由于无法访问我的Javascript函数，我现在的默认webpacker出现了问题.

I am trying to update a Rails 3 app to Rails 6 and I have problems with the now default webpacker since my Javascript functions are not accessible.

我得到:所有js函数触发器的ReferenceError: Can't find variable: functionName.

I get: ReferenceError: Can't find variable: functionName for all js function triggers.

我所做的是:

• 在/app/javascript
中创建一个app_directory
• 将我的开发javascript文件复制到app_directory中，并将其重命名为index.js
• 将console.log('Hello World from Webpacker');添加到index.js
• 将import "app_directory";添加到/app/javascript/packs/application.js

• 已添加到/config/initializers/content_security_policy.rb:

• create an app_directory in /app/javascript
• copied my development javascript file into the app_directory and renamed it to index.js
• added console.log('Hello World from Webpacker'); to index.js
• added import "app_directory"; to /app/javascript/packs/application.js

• added to /config/initializers/content_security_policy.rb:

Rails.application.config.content_security_policy do |policy|
  policy.connect_src :self, :https, "http://localhost:3035", "ws://localhost:3035" if Rails.env.development?
end

我将"Webpacker的Hello World"登录到控制台，但是尝试在浏览器中通过<div id="x" onclick="functionX()"></div>访问简单的JS函数时，出现参考错误.

I get 'Hello World from Webpacker' logged to console, but when trying to access a simple JS function through <div id="x" onclick="functionX()"></div> in the browser I get the reference error.

我了解到资产管道已被webpacker取代，这对于包含模块来说应该是很好的选择，但是我应该如何包含简单的JS函数呢?我想念什么?

I understand that the asset pipeline has been substituted by webpacker, which should be great for including modules, but how should I include simple JS functions? What am I missing?

提前谢谢吗?

推荐答案

有关从旧资产管道转换为新的webpacker处事方式的说明，您可以在此处查看:

For instructions on moving from the old asset pipeline to the new webpacker way of doing things, you can see here:

https://www .calleerlandsson.com/replacing-sprockets-with-webpacker-for-javascript-in-rails-5-2/

这是在Rails 5.2中从资产管道移动到webpacker的方法，它使您了解Rails 6中的不同之处，因为webpacker是javascript的默认设置.特别是:

This is a howto for moving from the asset pipeline to webpacker in Rails 5.2, and it gives you an idea of how things are different in Rails 6 now that webpacker is the default for javascript. In particular:

现在是时候将所有应用程序JavaScript代码从 app/assets/javascripts/到app/javascript/.

Now it’s time to move all of your application JavaScript code from app/assets/javascripts/ to app/javascript/.

要将它们包含在JavaScript包中，请确保在 app/javascript/pack/application.js:

To include them in the JavaScript pack, make sure to require them in app/javascript/pack/application.js:

require('your_js_file')

因此，像这样在app/javascript/hello.js中创建文件:

So, create a file in app/javascript/hello.js like this:

console.log("Hello from hello.js");

然后在app/javascript/packs/application.js中添加以下行:

require("hello")

(请注意，不需要扩展名)

(note that the extension isn't needed)

现在，您可以在浏览器控制台打开的情况下加载页面，并看到您好！"控制台中的消息.只需在app/javascript目录中添加所需的内容，或者创建子目录以使代码井井有条.

Now, you can load up a page with the browser console open and see the "Hello!" message in the console. Just add whatever you need in the app/javascript directory, or better yet create subdirectories to keep your code organized.

更多信息:

这个问题被诅咒了.以前接受的答案不仅是错误的，而且是极其错误的错误，而最受争议的答案仍然是在国家英里之外的地方.

This question is cursed. The formerly accepted answer is not just wrong but grotesquely wrong, and the most upvoted answer is still missing the mark by a country mile.

anode84仍在尝试按旧方法执行操作，如果尝试这样做，webpacker将会妨碍您的工作.当您移至webpacker时，您必须完全改变使用javascript的方式并考虑javascript.没有作用域问题".当您将代码放入Web Pack中时，它是独立的，并且您可以使用导入/导出在文件之间共享代码.默认情况下，什么都不是全局的.

anode84 above is still trying to do things the old way, and webpacker will get in your way if you try that. You have to completely change the way you do javascript and think about javascript when you move to webpacker. There is no "scoping issue". When you put code in a web pack it's self-contained and you use import/export to share code between files. Nothing is global by default.

我明白为什么这令人沮丧.您可能像我一样，习惯于在javascript文件中声明一个函数，然后在您的HTML文件中调用它.或者只是在HTML文件的末尾添加一些JavaScript.我从1994年开始从事网络编程(不是错别字)，所以我已经看到一切都在发展. Java语言已经发展.您必须学习新的做事方式.

I get why this is frustrating. You're probably like me, and accustomed to declaring a function in a javascript file and then calling it in your HTML file. Or just throwing some javascript at the end of your HTML file. I have been doing web programming since 1994 (not a typo), so I've seen everything evolve multiple times. Javascript has evolved. You have to learn the new way of doing things.

如果要向表单或其他内容添加操作，则可以在app/javascript中创建一个文件，该文件可以执行您想要的操作.要获取数据，可以使用数据属性，隐藏字段等.如果该字段不存在，则代码不会运行.

If you want to add an action to a form or whatever, you can create a file in app/javascript that does what you want. To get data to it, you can use data attributes, hidden fields, etc. If the field doesn't exist, then the code doesn't run.

这是一个您可能会发现有用的示例.如果表单具有Google reCAPTCHA并且用户在提交表单时未选中该框，我将使用它来显示弹出窗口:

Here's an example that you might find useful. I use this for showing a popup if a form has a Google reCAPTCHA and the user hasn't checked the box at the time of form submission:

// For any form, on submit find out if there's a recaptcha
// field on the form, and if so, make sure the recaptcha
// was completed before submission.
document.addEventListener("turbolinks:load", function() {
  document.querySelectorAll('form').forEach(function(form) {
    form.addEventListener('submit', function(event) {
      const response_field = document.getElementById('g-recaptcha-response');
      // This ensures that the response field is part of the form
      if (response_field && form.compareDocumentPosition(response_field) & 16) {
        if (response_field.value == '') {
          alert("Please verify that you are not a robot.");
          event.preventDefault();
          event.stopPropagation();
          return false;
        }
      }
    });
  });
});

请注意，这是独立的.它不依赖于任何其他模块，也没有其他依赖于它的模块.您只需在包中要求它，它将监视所有表单提交.

Note that this is self-contained. It does not rely on any other modules and nothing else relies on it. You simply require it in your pack(s) and it will watch all form submissions.

这是在加载页面时加载带有geojson叠加层的google地图的另一个示例:

Here's one more example of loading a google map with a geojson overlay when the page is loaded:

document.addEventListener("turbolinks:load", function() {
  document.querySelectorAll('.shuttle-route-version-map').forEach(function(map_div) {
    let shuttle_route_version_id = map_div.dataset.shuttleRouteVersionId;
    let geojson_field = document.querySelector(`input[type=hidden][name="geojson[${shuttle_route_version_id}]"]`);

    var map = null;

    let center = {lat: 36.1638726, lng: -86.7742864};
    map = new google.maps.Map(map_div, {
      zoom: 15.18,
      center: center
    });

    map.data.addGeoJson(JSON.parse(geojson_field.value));

    var bounds = new google.maps.LatLngBounds();
    map.data.forEach(function(data_feature) {
      let geom = data_feature.getGeometry();
      geom.forEachLatLng(function(latlng) {
        bounds.extend(latlng);
      });
    });
    map.setCenter(bounds.getCenter());
    map.fitBounds(bounds); 
  });
});

页面加载后，我会在类中找到"shuttle-route-version-map"类的div.对于我找到的每一个，数据属性"shuttleRouteVersionId"(data-shuttle-route-version-id)包含路由的ID.我将geojson存储在一个隐藏的字段中，给定该ID，可以很容易地查询它，然后初始化地图，添加geojson，然后根据该数据设置地图中心和边界.同样，除了Google Maps功能之外，它是独立的.

When the page loads, I look for divs with the class "shuttle-route-version-map". For each one that I find, the data attribute "shuttleRouteVersionId" (data-shuttle-route-version-id) contains the ID of the route. I have stored the geojson in a hidden field that can be easily queried given that ID, and I then initialize the map, add the geojson, and then set the map center and bounds based on that data. Again, it's self-contained except for the Google Maps functionality.

您还可以学习如何使用导入/导出共享代码，这确实很强大.

You can also learn how to use import/export to share code, and that's really powerful.

因此，另外一个显示了如何使用导入/导出.这是一段简单的代码，它设置了一个监视程序"来监视您的位置:

So, one more that shows how to use import/export. Here's a simple piece of code that sets up a "watcher" to watch your location:

var driver_position_watch_id = null;

export const watch_position = function(logging_callback) {
  var last_timestamp = null;

  function success(pos) {
    if (pos.timestamp != last_timestamp) {
      logging_callback(pos);
    }
    last_timestamp = pos.timestamp;
  }

  function error(err) {
    console.log('Error: ' + err.code + ': ' + err.message);
    if (err.code == 3) {
      // timeout, let's try again in a second
      setTimeout(start_watching, 1000);
    }
  }

  let options = {
    enableHighAccuracy: true,
    timeout: 15000, 
    maximumAge: 14500
  };

  function start_watching() {
    if (driver_position_watch_id) stop_watching_position();
    driver_position_watch_id = navigator.geolocation.watchPosition(success, error, options);
    console.log("Start watching location updates: " + driver_position_watch_id);  
  }

  start_watching();
}

export const stop_watching_position = function() {
  if (driver_position_watch_id) {
    console.log("Stopped watching location updates: " + driver_position_watch_id);
    navigator.geolocation.clearWatch(driver_position_watch_id);
    driver_position_watch_id = null;
  }
}

导出两个函数:"watch_position"和"stop_watching_position".要使用它，请将这些功能导入另一个文件.

That exports two functions: "watch_position" and "stop_watching_position". To use it, you import those functions in another file.

import { watch_position, stop_watching_position } from 'watch_location';

document.addEventListener("turbolinks:load", function() {
  let lat_input = document.getElementById('driver_location_check_latitude');
  let long_input = document.getElementById('driver_location_check_longitude');

  if (lat_input && long_input) {
    watch_position(function(pos) {
      lat_input.value = pos.coords.latitude;
      long_input.value = pos.coords.longitude;
    });
  }
});

页面加载后，我们会查找名为"driver_location_check_latitude"和"driver_location_check_longitude"的字段.如果它们存在，我们将设置一个带有回调的观察程序，当这些字段更改时，回调函数将使用纬度和经度填充这些字段.这是在模块之间共享代码的方法.

When the page loads, we look for fields called "driver_location_check_latitude" and "driver_location_check_longitude". If they exist, we set up a watcher with a callback, and the callback fills in those fields with the latitude and longitude when they change. This is how to share code between modules.

因此，这又是一种非常的不同处理方式.正确地模块化和组织后，您的代码将更清晰，更可预测.

So, again, this is a very different way of doing things. Your code is cleaner and more predictable when modularized and organized properly.

这就是未来，因此与之抗争(并设置"window.function_name"与之抗争)将无济于事.

This is the future, so fighting it (and setting "window.function_name" is fighting it) will get you nowhere.

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