grunt-sri


This tool generates a JSON manifest of file hashes & sub-resource integrity data.

Install

``shell
npm install --save-dev grunt-sri
`

Usage

Add the following to your Gruntfile.js:

`js
module.exports = function (grunt) {
"use strict";

grunt.loadNpmTasks("grunt-sri");

grunt.initConfig({
"sri": {

// Use the default settings for everything in ./public/css
"bobsDefaultTask": {
"src": [
"public/*/.css"
]
},

// Create a second manifest with custom settings
"janesCustomTask": {
"options": {
"algorithms": ["sha256"],
"dest": "./public/sri-directives.json",
"targetProp": "payload"
},
"files": [
{
src: "public/css/example.css",
type: "text/css",
id: "cssfile1"
},
{
src: "public/css/other.css"
}
]
}

}

});

grunt.registerTask("default", ["sri"]);
};
`

Run the command grunt. The manifest file will be created.

Options

* String dest: Target JSON file.
Default "./payload.json"
* Boolean merge: Merge results with existing JSON file.
Default false (overwrite)
* Array algorithms: List of desired hash algorithms.
Default ["sha256", "sha512"]
* String targetProp: Target JS object property name.
Default null
* Boolean pretty: Stringify the JSON output in a pretty format.
Default false

Manifest

Metadata is stored in JSON format.

* The default manifest dest is ./payload.json.
* File paths are relative to the CWD of Grunt.
This should be the project root.
* File identifiers are prefixed with the "@" symbol.
If no ID is specified, the path will be used.

Example:

`json
{
"@cssfile1": {
"path": "public/css/example.css",
"type": "text/css",
"integrity": "type:text/css sha256-XXXX sha512-XXXXXXXX",
"hashes": {
"sha256": "XXXX",
"sha512": "XXXXXXXX"
}
}
}
`

$3

Data from the manifest can be loaded into markup.
Use the integrity property for SRI integrity attributes, a hash from hashes as a URL parameter for client-side caching, etc.

#### PHP

`php
// In production, consider compiling JSON to PHP assoc arrays
$payload = json_decode(file_get_contents("./payload.json"), true);
$sri = function (id) {
return $payload["payload"][id];
}

$element = " href='/style.css?cache={ sri("@cssfile1")["hashes"]["sha256"] }'
integrity='{ $sri("@cssfile1")["integrity"] }'
rel='stylesheet'>";
`

#### JavaScript

Note: Node apps should use subresource or handlebars-helper-sri, which don't require a build step.

`js
// ES6
var payload = require("./payload.json");
var sri = (id) => payload.payload[id];

var element = href='/style.css?cache=${ sri("@cssfile1").hashes.sha256 }'
integrity='${ sri("@cssfile1").integrity }'
rel='stylesheet'>;
``

SemVer

This tool follows SemVer from v0.1.0, as SRI is now a W3C recommendation.

Changes to the V1 SRI spec will be tracked with minor releases.