filter-where

filter-where

Filter an array using any combination of scalars, object queries, functions or regular expressions.

where(query) ⇒ function ⏏

Kind: Exported function

Example
Say you have a recordset:

> data = [
    { name: 'Dana', age: 30 },
    { name: 'Yana', age: 20 },
    { name: 'Zhana', age: 10 }
]

You can return records with properties matching an exact value:

> data.filter(where({ age: 10 }))
[ { name: 'Zhana', age: 10 } ]

or where NOT the value (prefix the property name with !)

> data.filter(where({ '!age': 10 }))
[ { name: 'Dana', age: 30 }, { name: 'Yana', age: 20 } ]

match using a function:

> function over10(age){ return age > 10; }
> data.filter(where({ age: over10 }))
[ { name: 'Dana', age: 30 }, { name: 'Yana', age: 20 } ]

match using a regular expression

> data.filter(where({ name: /ana/ }))
[ { name: 'Dana', age: 30 },
  { name: 'Yana', age: 20 },
  { name: 'Zhana', age: 10 } ]

You can query to any arbitrary depth. So with deeper data, like this:

> deepData = [
    { name: 'Dana', favourite: { colour: 'light red' } },
    { name: 'Yana', favourite: { colour: 'dark red' } },
    { name: 'Zhana', favourite: { colour: [ 'white', 'red' ] } }
]

get records with favourite.colour values matching /red/

> deepData.filter(where({ favourite: { colour: /red/ } }))
[ { name: 'Dana', favourite: { colour: 'light red' } },
  { name: 'Yana', favourite: { colour: 'dark red' } } ]

if the value you're looking for maybe part of an array, prefix the property name with +. Now Zhana is included:

> deepData.filter(where({ favourite: { '+colour': /red/ } }))
[ { name: 'Dana', favourite: { colour: 'light red' } },
  { name: 'Yana', favourite: { colour: 'dark red' } },
  { name: 'Zhana', favourite: { colour: [ 'white', 'red' ] } } ]

you can combine any of the above by supplying an array of queries. Records will be returned if any of the queries match:

> const nameBeginsWithY = { name: /^Y/ }
> const faveColourIncludesWhite = { favourite: { '+colour': 'white' } }

> deepData.filter(where([ nameBeginsWithY, faveColourIncludesWhite ]))
[ { name: 'Yana', favourite: { colour: 'dark red' } },
  { name: 'Zhana', favourite: { colour: [ 'white', 'red' ] } } ]

© 2016-18 Lloyd Brookes <[email protected]>. Documented by jsdoc-to-markdown.