A library that calculates the CSP hash for amp-script

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434912.9.03 months ago3 years agoMinified + gzip package size for @ampproject/toolbox-script-csp in KB


AMP-Toolbox Script CSP
npm version
Calculates the Content Security Policy (CSP) hash for the given script in the format expected by amp-script.
CSP is required when using amp-script with inline or cross-origin scripts.


Install via:
$ npm install @ampproject/toolbox-script-csp

Using the module

The module exposes a single function, calculateHash(src, options?).
src can be either a string (in which case UTF8 encoding is assumed) or a DataView such as a Buffer.
options is used to override the default options.


  • algorithm overrides the hashing algorithm to use. Currently, the only
algorithm supported by `amp-script` is `sha384` which is the default value.


Here is an example on how to use the calculateHash function to generate an amp-script CSP header.
Note that both leading and trailing whitespace is included in calculating the hash and must exactly match the whitespace used in the inline script.
const {calculateHash} = require('@ampproject/toolbox-script-csp');

const script = `
    const subject = 'world';
    console.log('Hello, ' + subject);

const hash = calculateHash(script);

console.log(hash);  // sha384-xRxb5sv13at6tVgZET4JLmf89TSZP10HjCGXVqO9bKWVXB0asV2jLrsDN8v4zX6j

The generated hash can be used in a <meta> tag this way:
<!doctype html>
<html ⚡>

  <meta name="amp-script-src" content="sha384-xRxb5sv13at6tVgZET4JLmf89TSZP10HjCGXVqO9bKWVXB0asV2jLrsDN8v4zX6j">

    <amp-script layout="container" script="example"></amp-script>

    <script id="example" type="text/plain" target="amp-script">
    const subject = 'world';
    console.log('Hello, ' + subject);