Koa-manifest-rev NPM

koa-manifest-rev

Dynamically load assets into your views from your rev-manifest.json manifest revision file (e.g. <script src="{{ manifest('foo.js'); }}"></script> returns <script src="/foo-0775041dd4.js"></script> when rendered).
Works with any templating engine, such as pug, ejs, or nunjucks. Inspired by express-rev and built for koa.

Install

npm:

npm install koa-manifest-rev

yarn:

yarn add koa-manifest-rev

Usage

Require the package and include the middleware

import Koa from 'koa';
import koaManifestRev from 'koa-manifest-rev';
import path from 'path';

const app = new Koa();

app.use(koaManifestRev({
  manifest: path.join(__dirname, 'build', 'rev-manifest.json'),
  prepend: '/'
}));

Call the manifest(str) helper function in your views when you need to include assets (requires a templating engine).

pug:

html
  head
    title Foo
  body
    h1 Foo
    script(src=manifest('foo.js'))

ejs

<html>
  <head>
    <title>Foo</title>
  </head>
  <body>
    <h1>Foo</h1>
    <script src="<%= manifest('foo.js'); %>"></script>
  </body>
</html>

nunjucks (via koa-nunjucks-promise):

<html>
  <head>
    <title>Foo</title>
  </head>
  <body>
    <h1>Foo</h1>
    <script src="{{ manifest('foo.js'); }}"></script>
  </body>
</html>

API

koaManifestRev(options) - accepts a required options argument for setup. Returns middleware for use in app.use statement (which in turn binds to ctx.state a helper function called manifest). Here are the properties accepts in the options argument.
- manifest (required) - path to a valid rev-manifest.json file (e.g. as built by gulp-rev or gulp-rev-all)
- prepend (optional) - string to prepend before file paths rendered after lookup (e.g. if you type {{ manifest('foo.js'); }} in your view, and you have passed prepend: '/dist/' in your setup, then your tag would render as <script src="/dist/foo-0775041dd4.js"></script> (defaults to /)
manifest(str) - the helper function bound to ctx.state when koaManifestRev middleware is included in your app. Returns the string found from a lookup in your rev-manifest.json file for the str argument passed (e.g. if you type {{ manifest('foo.js'); }} in your view, then it returns for the value of the foo.js property as defined in your manifest file, such as foo-0775041dd4.js). If the found is not found, then the input str argument is returned.