How to Retrieve Non-Enumerable Inherited Property Names in JavaScript?

Obtaining Non-Enumerable Inherited Property Names of an Object in JavaScript

JavaScript provides various methods for accessing object properties based on specific requirements. However, none of these methods allow for the retrieval of non-enumerable, non-own properties. This article explores alternative approaches to extracting such properties.

Solution: Leveraging getOwnPropertyNames and Prototype Chaining

Since Object.getOwnPropertyNames() can retrieve non-enumerable properties, it can be combined with prototype chain traversal. The following JavaScript function, getAllProperties(), iterates through the prototype chain of an object and compiles a list of all its non-enumerable, non-own properties:

function getAllProperties(obj){</p><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">var allProps = []
  , curr = obj
do{
    var props = Object.getOwnPropertyNames(curr)
    props.forEach(function(prop){
        if (allProps.indexOf(prop) === -1)
            allProps.push(prop)
    })
}while(curr = Object.getPrototypeOf(curr))
return allProps

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}

Example Usage

To demonstrate the functionality of the getAllProperties() function, consider the following array object:

console.log(getAllProperties([1,2,3]));

Output:

[ 'length' ]

The output lists the non-enumerable property 'length', which belongs to the Array.prototype chain.

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