hugo/content/en/functions/js/Build.md

title, description, categories, keywords, params

title	description	categories	keywords	params
js.Build	Bundle, transpile, tree shake, and minify JavaScript resources.			functions_and_methods aliases returnType signatures resource.Resource js.Build [OPTIONS] RESOURCE

The js.Build function uses the evanw/esbuild package to:

• Bundle
• Transpile (TypeScript and JSX)
• Tree shake
• Minify
• Create source maps

{{ with resources.Get "js/main.js" }}
  {{$opts := dict
    "minify" (cond hugo.IsDevelopment false true)
    "sourceMap" (cond hugo.IsDevelopment "linked" "none")
  }}
  {{ with . | js.Build $opts }}
    {{ if hugo.IsDevelopment }}
      <script src="{{ .RelPermalink }}"></script>
    {{ else }}
      {{ with . | fingerprint }}
        <script src="{{ .RelPermalink }}" integrity="{{ .Data.Integrity }}" crossorigin="anonymous"></script>
      {{ end }}
    {{ end }}
  {{ end }}
{{ end }}

Options

targetPath

(string) If not set, the source path will be used as the base target path. Note that the target path's extension may change if the target MIME type is different, e.g. when the source is TypeScript.

format

(string) The output format. One of: iife, cjs, esm. Default is iife, a self-executing function, suitable for inclusion as a <script> tag.

{{% include "/_common/functions/js/options.md" %}}

Import JS code from the assets directory

js.Build has full support for Hugo's unified file system. You can see some simple examples in this test project, but in short this means that you can do this:

import { hello } from 'my/module';

And it will resolve to the top-most index.{js,ts,tsx,jsx} inside assets/my/module in the layered file system.

import { hello3 } from 'my/module/hello3';

Will resolve to hello3.{js,ts,tsx,jsx} inside assets/my/module.

Any imports starting with . are resolved relative to the current file:

import { hello4 } from './lib';

For other files (e.g. JSON, CSS) you need to use the relative path including any extension, e.g:

import * as data from 'my/module/data.json';

Any imports in a file outside assets or that does not resolve to a component inside assets will be resolved by ESBuild with the project directory as the resolve directory (used as the starting point when looking for node_modules etc.). Also see hugo mod npm pack. If you have any imported npm dependencies in your project, you need to make sure to run npm install before you run hugo build.

Also note the new params option that can be passed from template to your JS files, e.g.:

{{ $js := resources.Get "js/main.js" | js.Build (dict "params" (dict "api" "https://example.org/api")) }}

And then in your JS file:

import * as params from '@params';

Hugo will, by default, generate a assets/jsconfig.json file that maps the imports. This is useful for navigation/intellisense help inside code editors, but if you don't need/want it, you can turn it off.

Node.js dependencies

Use the js.Build function to include Node dependencies.

Any imports in a file outside assets or that does not resolve to a component inside assets will be resolved by esbuild with the project directory as the resolve directory (used as the starting point when looking for node_modules etc.). Also see hugo mod npm pack. If you have any imported npm dependencies in your project, you need to make sure to run npm install before you run hugo build.

The start directory for resolving npm packages (aka. packages that live inside a node_modules directory) is always the main project directory.

Note

If you're developing a theme/component that is supposed to be imported and depends on dependencies inside package.json, we recommend reading about hugo mod npm pack, a tool to consolidate all the npm dependencies in a project.

Examples

{{ $built := resources.Get "js/index.js" | js.Build "main.js" }}

Or with options:

{{ $externals := slice "react" "react-dom" }}
{{ $defines := dict "process.env.NODE_ENV" `"development"` }}

{{ $opts := dict "targetPath" "main.js" "externals" $externals "defines" $defines }}
{{ $built := resources.Get "scripts/main.js" | js.Build $opts }}
<script src="{{ $built.RelPermalink }}" defer></script>