How do I remove objects from a JavaScript associative array?

Action time: delete operator

To help you transform from a JavaScript "padawan" into a "Jedi Knight", let's dissect the practical use of the delete operator in JavaScript.

Deleting object properties

Using delete is like performing digital magic: object properties vanish. Here's how we conjure this sorcery:

let associativeArray = {'key1': '42', 'key2': 'answer to life, universe, and everything'};
delete associativeArray['key1']; // 'key1' has left the building.


Memory management

The obliteration of the property does not involve immediate memory deallocation. It merely waves a flag at the JavaScript garbage collector to acknowledge that the property's memory can be collected during its rounds.

The caveat: performance

Remember, nothing's free in this world, using delete may affect the performance of JavaScript engines and complicate optimization due to the resulting changes in object structure.

Code cookery: working with arrays

Working with associative arrays (objects) in JS can be a joy or curse, depending on your mastery of certain array manipulation techniques.

The slice and dice: Array.splice

When working with good ol' index based arrays, Array#splice comes in handy for eliminating an element mercilessly:

let array = [1, 2, 3, 4];
array.splice(1, 1); // '2' is spliced out. Array is now leaner: [1, 3, 4]


Last one out, close the door: Array.pop

If you need to kick the last one out, use Array#pop(). No need to drag everyone else along:

let array = [1, 2, 3, 4];
array.pop(); // ’4' has left the party. Array is now [1, 2, 3]


Robust and efficient JavaScript

Creating JavaScript code that's robust, efficient, and marketable to any prospective employer requires insight.

Respect the array

Manipulating arrays with delete may cause inaccurate array size representation. Keep the array's size honest after property deletion.

Delete operator: a versatile tool

The delete operator works well with both dot notation (obj.key) and bracket notation (obj['key']).

Debug in style

If you play your cards right, any alert message will bow to your will to display object property values

alert(associativeArray['key2']); // Wakes up your browser to scream out 'value2'
