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javascriptwebpackejswebpack-dev-serverhtml-webpack-plugin

Fails to compile, when I try to use include with EJS files. (Error: Child compilation failed.)

I already made this a github issue, but I am suspecting there might be something trivial, that I just don't know about.

I would really appreciate some input to help me with the debuging.

Demo:

https://github.com/andrasna/html-ejs-webpack-config-issue-demo

index.ejs

<% const title = 'Hello' %>

<%- include('partial') -%>

<h1><%= `${title} World` %></h1>

webpack.config.js 

const HtmlWebpackPlugin = require('html-webpack-plugin')

module.exports = {
  plugins: [
    new HtmlWebpackPlugin({
      filename: 'index.html',
      template: 'index.ejs',
    })
  ]
}

Expected behaviour

I am trying to include one EJS file into another, as per documentation:

https://ejs.co/#docs

<%- include('header'); -%>
<h1>
  Title
</h1>
<p>
  My page
</p>
<%- include('footer'); -%>

What I would expect, is for the HTML within partial.ejs to be included in the index.ejs file.

Current behaviour

I get "Error: Child compilation failed" (see full error message below).

However, EJS gets compiled if I remove the line with the include in index.ejs. Which is why I think the problem is specific to includes.

Any ideas?

Error message

> npm start

> html-ejs-webpack-config-issue-demo@1.0.0 start /Users/user/Dev/html-ejs-webpack-config--issue-demo
> webpack-dev-server --mode development

ℹ ｢wds｣: Project is running at http://localhost:8080/
ℹ ｢wds｣: webpack output is served from /
ℹ ｢wds｣: Content not from webpack is served from /Users/user/Dev/html-ejs-webpack-config--issue-demo
✖ ｢wdm｣: Hash: f9f8666f87ab7acd22cd
Version: webpack 4.41.2
Time: 595ms
Built at: 19/10/2019 15:34:18
     Asset      Size  Chunks             Chunk Names
index.html  1.72 KiB          [emitted]  
   main.js   360 KiB    main  [emitted]  main
Entrypoint main = main.js
[0] multi (webpack)-dev-server/client?http://localhost:8080 ./src 40 bytes {main} [built]
[./node_modules/ansi-html/index.js] 4.16 KiB {main} [built]
[./node_modules/ansi-regex/index.js] 135 bytes {main} [built]
[./node_modules/html-entities/index.js] 231 bytes {main} [built]
[./node_modules/loglevel/lib/loglevel.js] 7.68 KiB {main} [built]
[./node_modules/strip-ansi/index.js] 161 bytes {main} [built]
[./node_modules/webpack-dev-server/client/index.js?http://localhost:8080] (webpack)-dev-server/client?http://localhost:8080 4.29 KiB {main} [built]
[./node_modules/webpack-dev-server/client/overlay.js] (webpack)-dev-server/client/overlay.js 3.51 KiB {main} [built]
[./node_modules/webpack-dev-server/client/socket.js] (webpack)-dev-server/client/socket.js 1.53 KiB {main} [built]
[./node_modules/webpack-dev-server/client/utils/createSocketUrl.js] (webpack)-dev-server/client/utils/createSocketUrl.js 2.89 KiB {main} [built]
[./node_modules/webpack-dev-server/client/utils/log.js] (webpack)-dev-server/client/utils/log.js 964 bytes {main} [built]
[./node_modules/webpack-dev-server/client/utils/reloadApp.js] (webpack)-dev-server/client/utils/reloadApp.js 1.59 KiB {main} [built]
[./node_modules/webpack-dev-server/client/utils/sendMessage.js] (webpack)-dev-server/client/utils/sendMessage.js 402 bytes {main} [built]
[./node_modules/webpack/hot sync ^\.\/log$] (webpack)/hot sync nonrecursive ^\.\/log$ 170 bytes {main} [built]
[./src/index.js] 0 bytes {main} [built]
    + 18 hidden modules

ERROR in   Error: Child compilation failed:
  Module build failed (from ./node_modules/html-webpack-plugin/lib/loader.js):
  SyntaxError: Unexpected token )

  - Function

  - lodash.js:14870 
    [html-ejs-webpack-config--issue-demo]/[lodash]/lodash.js:14870:16

  - lodash.js:473 apply
    [html-ejs-webpack-config--issue-demo]/[lodash]/lodash.js:473:27

  - lodash.js:15254 
    [html-ejs-webpack-config--issue-demo]/[lodash]/lodash.js:15254:16

  - lodash.js:475 apply
    [html-ejs-webpack-config--issue-demo]/[lodash]/lodash.js:475:27

  - lodash.js:6563 
    [html-ejs-webpack-config--issue-demo]/[lodash]/lodash.js:6563:16

  - lodash.js:14869 Function.template
    [html-ejs-webpack-config--issue-demo]/[lodash]/lodash.js:14869:20


  - SyntaxError: Unexpected token )

  - compiler.js:79 childCompiler.runAsChild
    [html-ejs-webpack-config--issue-demo]/[html-webpack-plugin]/lib/compiler.js:79:16

  - Compiler.js:343 compile
    [html-ejs-webpack-config--issue-demo]/[webpack]/lib/Compiler.js:343:11

  - Compiler.js:681 hooks.afterCompile.callAsync.err
    [html-ejs-webpack-config--issue-demo]/[webpack]/lib/Compiler.js:681:15


  - Hook.js:154 AsyncSeriesHook.lazyCompileHook
    [html-ejs-webpack-config--issue-demo]/[tapable]/lib/Hook.js:154:20

  - Compiler.js:678 compilation.seal.err
    [html-ejs-webpack-config--issue-demo]/[webpack]/lib/Compiler.js:678:31


  - Hook.js:154 AsyncSeriesHook.lazyCompileHook
    [html-ejs-webpack-config--issue-demo]/[tapable]/lib/Hook.js:154:20

  - Compilation.js:1423 hooks.optimizeAssets.callAsync.err
    [html-ejs-webpack-config--issue-demo]/[webpack]/lib/Compilation.js:1423:35



Child html-webpack-plugin for "index.html":
     1 asset
    Entrypoint undefined = index.html
    [./node_modules/html-webpack-plugin/lib/loader.js!./index.ejs] 922 bytes {0} [built] [failed] [1 error]

    ERROR in ./index.ejs (./node_modules/html-webpack-plugin/lib/loader.js!./index.ejs)
    Module build failed (from ./node_modules/html-webpack-plugin/lib/loader.js):
    SyntaxError: Unexpected token )
        at Function (<anonymous>)
        at /Users/user/Dev/html-ejs-webpack-config--issue-demo/node_modules/lodash/lodash.js:14870:16
        at apply (/Users/user/Dev/html-ejs-webpack-config--issue-demo/node_modules/lodash/lodash.js:473:27)
        at /Users/user/Dev/html-ejs-webpack-config--issue-demo/node_modules/lodash/lodash.js:15254:16
        at apply (/Users/user/Dev/html-ejs-webpack-config--issue-demo/node_modules/lodash/lodash.js:475:27)
        at /Users/user/Dev/html-ejs-webpack-config--issue-demo/node_modules/lodash/lodash.js:6563:16
        at Function.template (/Users/user/Dev/html-ejs-webpack-config--issue-demo/node_modules/lodash/lodash.js:14869:20)
        at Object.module.exports (/Users/user/Dev/html-ejs-webpack-config--issue-demo/node_modules/html-webpack-plugin/lib/loader.js:28:22)
ℹ ｢wdm｣: Failed to compile.
Solution

  • use the ejs-compiled-loader with the HtmlWebpackPlugin

    npm install --save-dev ejs-compiled-loader

    change webpack.config.js to:

    const HtmlWebpackPlugin = require('html-webpack-plugin')

module.exports = {
  plugins: [
    new HtmlWebpackPlugin({
      filename: 'index.html',
      template: '!!ejs-compiled-loader!index.ejs', //Here is the Loader plugged in
    })
  ]
}

    (as described here)

    Then alter your template to valid EJS. HtmlWebpackPlugin says: "By default (if you don't specify any loader in any way) a fallback lodash loader kicks in." It renders the template with lodash as a minimalistic loader. This is why your errors come from lodash.js .

    index.ejs:

    <% title = 'Hello' %>

<%- include partial -%>

<h1><%= title%> World</h1>

    Then npm start and your fresh compiled "Lorem Ipsum ...Hello World" will be served on your localhost.

    Or npx webpack --mode=development to get your 'dist/index.html' to enjoy the source :)