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Cloning objects in JavaScript

adamkdean profile image Adam K Dean ・1 min read

Just a quick snippet post today.

A great way to clone objects in JavaScript and break references is to serialize and deserialize the object. The process of converting it to a JSON string and back into an object severs any references. Unfortunately, it also breaks certain types such as Date and probably RegEx too.

var clone = JSON.parse(JSON.stringify(original));

A better way (I've found) to clone objects while retaining types is to use jQuery.extend.

// Shallow copy
var newObject = jQuery.extend({}, oldObject);

// Deep copy
var newObject = jQuery.extend(true, {}, oldObject);

There are other, quicker ways, but when you can run 120,000 deep copies a second, is that extra microsecond really worth it?

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Adam K Dean


Principal Network Engineer / Master of Engineering (Mechanical) student


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