README
DRA - Dual Reference Array
Makes an array's object available through the same array's namespace, through a property, keeping the index untouched. This is just a pattern, not a API neither a framework. I never saw something like this before, so decided to study it.
Long history version
Read my detailed article at Medium
What it must do
- The Array: Mind a array, with a collection (a array with objects and, at least, one common property);
- The Property: Select a common property of the collection, with a unique string value;
- The DRA: In the same array, create a property with the string value, which makes the collection available by it index (the default way) AND it string value, like a property.
Play with it
https://tonicdev.com/jotafeldmann/dra-dual-reference-array
Example
npm install dra-dual-reference-array
var DRA = require ('dra-dual-reference-array');
var
fields = [ // Our array
{
id : 0,
fieldName : 'email', // It's a common property, with unique values
label : 'Email',
data : { dummy : 'whoomy' }
},
{
id : 1,
fieldName : 'another', // Again
label : 'Another field'
}
]
;
// At this time, I just can access the array, through the index
console.log ( fields[0] ); // Object {...}
// Now, the magic
fields = DRA ( fields , 'fieldName' );
// Then, the same array's value is available by it's common property unique name
console.log ( fields._email ); // Object {...}
// If some property is changed, the change is reflected in both ways
fields._email.label = 'Devs are disciples of Thomas the Apostle';
console.log ( fields._email.label , fields[0].label );
// 'Devs are disciples of Thomas the Apostle' , 'Devs are disciples of Thomas the Apostle'
// The versa is the same, the ARRAY's REFERENCE can be accessed in DUAL ways
fields[0].label = 'We need to see to believe, show me the code';
console.log ( fields._email.label , fields[0].label );
// 'We need to see to believe, show me the code' , 'We need to see to believe, show me the code'
// And the object comparison remains
fields[0] === fields._email // True
// BONUS: it keeps the array's length untouched
fields.length // 2
// BONUS: You can use the explicit method to achieve the same result and improve readability
// Suggestion by Raul Oliver
DRA.convertPropsToObject ( fields , 'fieldName' );
It uses the following JavaScript's capabilities:
- Set/Get a object's property in the Array form;
- When a Array got it value from another array, the portion of memory is a link to the another array. So, when that value change, the other array's value change too;
- Bonus: keeps the integrity of Array's length.
TODO
- Examples
- Tests
- Error throwing;
- Treat same name properties: duplicate indexes must generate a error or a property with a array (obj.fieldName[0], obj.fieldName[1]) and allow a function parameter for custom solutions;
- A option to change/remove the _ (underscore) of the names: by default, all properties contain _ (underscore) at first char position, to avoid collision with reserved words;
Real world application
- The DRA behavior looks like the Java LinkedMap from Apache's Commons Collections Behavior (thanks to @gilmargr for the insight)
- My last case: In Angular, convert the JSON array to $scope data;
- When developing a API's fields list validation, I can use the same namespace to iterate (array) or call the direct property's name;
- The first case: iterate through array of templates like objects, and access the properties directly, calling the name of the template.
License
MIT License © Jorge Feldmann (jotafeldmann)