Use filters to change how answers appear

To use filters, you need to know how to pass data from page to page.

The kit stores data from all answers that users give in a prototype, so that you can use or show the answers later. To change the format of how these answers appear, you can apply filters.

You can create your own filters or use existing Nunjucks filters in the kit. For example, you can use the Nunjucks upper filter to change the format of text to upper case:

{{ data['name'] | upper }}

Create a Nunjucks filter

Add your own filters to the app/filters.js file. Filters are written in JavaScript.

const govukPrototypeKit = require('govuk-prototype-kit')
const addFilter = govukPrototypeKit.views.addFilter

addFilter('uppercase', function (content) {
  return content.toUpperCase()

Then use it on a page like this:

{{ data['name'] | uppercase }}

Use HTML in a Nunjucks filter

If you want to use HTML in a filter, use the renderAsHTML option like this:

addFilter('bold', function (content) {
  return '<strong>' + content + '</strong>'
}, { renderAsHtml: true })

Then use it on a page like this:

{{ data['name'] | bold }}

You can also use these filters together:

{{ data['name'] | upper | bold }}