follows-order v1.0.0

follows-order

Checks that specific array elements or string characters appear only in a certain order. Packaged as a Node.js module.

Installation

npm install follows-order --save

The module exposes a single function.

Usage

Array Example

const followsOrder = require('follows-order')

const data = {
  name: "Test",
  description: "This is a test",
  module: "follows-order",
}

// Check to make sure that `name` precedes `description`.
// (Note: JavaScript does not guarantee object key order.
// This is only for the sake of example.)
followsOrder(Object.keys(data), ['name', 'description']) // true

String Example

const followsOrder = require('follows-order')

const data = 'test'

// Does the first "t" come before the first "e"?
followsOrder(data, 'te') // true

A Note on Duplicates

If an array or string is being checked to see if its order follows A, B, then the first B cannot appear before the first A does, even if the A, B pattern occurs later.

This is according to design: the module is made to enforce a certain order, not merely check for a pattern.

const followsOrder = require('follows-order')

const data = [1, 2, 1]

followsOrder(data, [1, 2]) // true
followsOrder(data, [2, 1]) // false, because in the data the first instance of 1 occurs before 2
followsOrder(data, [1, 2, 1]) // true

If you don’t want to deal with duplicate elements in your data, you’ll need to deduplicate the data yourself before you check it with follows-order.