DiffEx

A tool to extract key-value pairs by comparing (diffing) a template with an input string.

Installation

npm install flowxo/diffex

Usage

diffex is initialised with a template, which is used as a base for the diffing.

A template is a simple string with {{placeholder}} values. These placeholders will be replaced with data when the template is applied to an input string.

You should define your template variables inside {{ and }} curly braces. Don't include any spaces inside the curlys, as this will prevent the extractor from working correctly.

For example, these template variables are ok:

{{name}}
{{first_name}}
{{last-name}}

whereas these are invalid:

{{ name }}
{{first name}}
{{ last name }}

Create the diffex object like so:

var do = diffex(template);

Once you have the diffex object, there are two methods available: placeholders() and parse(input).

.placeholders()

Parses the template and outputs all found placeholders.

Example:

var diffex = require('diffex');
var template = '{{customer}} owes £{{amount}}.';
 
diffex(template).placeholders();
// -> ['customer', 'amount']

.parse(input)

Compares the template with an input, extracting the differences and outputting as key-value pairs.

var diffex = require('diffex');
var template = '{{customer}} owes £{{amount}}.';
var input = 'Bob owes £19.'
 
diffex(template).parse(input);
// -> { customer: 'Bob', amount: '19' }

Credit

The core diff algorithm was implemented by Neil Fraser, originally found here. The library is reproduced here under the Apache 2.0 license.

License

Apache 2.0