# AMP-Toolbox Script CSP
[](https://badge.fury.io/js/%40ampproject%2Ftoolbox-script-csp)
Calculates the [Content Security Policy (CSP)](https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP)
hash for the given script in the format expected by [`amp-script`](https://amp.dev/documentation/components/amp-script/).
CSP is required when using `amp-script` with inline or cross-origin scripts.
## Usage
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`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView)
such as a [`Buffer`](https://nodejs.org/api/buffer.html).
`options` is used to override the default options.
#### Options
* `algorithm` overrides the hashing algorithm to use. Currently, the only
algorithm supported by `amp-script` is `sha384` which is the default value.
### Example
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.
```javascript
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 `` tag this way:
```html
...
...
```