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Build Status Dependency Status js-semistandard-style

Checks whether or not an object fulfills a specified condition


Requires at least Node.js 6.x


npm install fulfills --save


const fulfills = require('fulfills');
const obj = {
  property: { subproperty: 'value' }
// Performant option – useful if the same condition is used over and over again 
const condition = fulfills.compile('property.subproperty = value OR property.subproperty = 123');
if (fulfills(obj, condition)) {
  // ... 
// Short option – useful if a condition will only be used once 
if (fulfills(obj, 'property.subproperty = value OR property.subproperty = 123')) {
  // ... 

Condition syntax

A condition has the syntax of:

property == value or just property

The == can be any supported comparison operator. If only a property is given then the condition will be true of the property contains a truthy value in the javascript sense.

Multiple conditions can be combined or modified through the use of logical operators and when doing so parantheses can be used to group them together into different groups.

Needlessly complex example

!(["abc adf sdaf sda f"][][][]=123) AND foo OR bar=abc OR foo="\\" OR foo[]=123 OR[][] != true

Property syntax

The property can be targeted at subproperties by appending them with a . before each level, like: property.subproperty.subpropertyOfSubproperty.

To look for a value in an array rather than compare the value to the array itself, then append [] to the property like: property[]

The array syntax and subproperties can be combined however one likes. For example: property.subproperty[][].propertyOfObjectInATwoLevelDeepArray

Complex property names can be specified like ["very complex property name"]. Values in suck property names can be escaped, like: ["property name including a \"funny\" char"]

Supported values

  • Simple strings – a single word containing just a-z needs no quotes. Example: foobar
  • Quoted stringes – multiple words or complex words needs to be quoted. Example: "a very long text". Supports escaping, like: "This is an escaped \" character"
  • Integers – a number containg just 0-9 chars
  • Booleans – when set to exactly true or false

Comparison operators

All work just like the javascript comparison operators does.

  • ===
  • == (alias: =)
  • !==
  • != (alias: <>)
  • <
  • >
  • <=
  • >=

Logical operators

  • OR (alias: ||)
  • AND (alias: &&)
  • NOT (alias: !)