How Can I Get the Keys and Key Count of a JavaScript Object?

Retrieving JavaScript Object Key List

A common task when working with JavaScript objects is retrieving the list of their keys. This can be useful for various purposes, such as iterating over the object's properties or validating input.

In this article, we'll explore a straightforward way to get the length and list of keys in a JavaScript object using the Object.keys() method.

Problem:

Consider the following JavaScript object:

var obj = {
   key1: 'value1',
   key2: 'value2',
   key3: 'value3',
   key4: 'value4'
}

How can we determine the number of keys in this object and obtain a list of those keys?

Solution:

The Object.keys() method is a convenient tool for retrieving an array containing the keys of a given object. Here's how you can use it to solve the problem:

var obj = {
   key1: 'value1',
   key2: 'value2',
   key3: 'value3',
   key4: 'value4'
}

var keys = Object.keys(obj);
console.log('obj contains ' + keys.length + ' keys: ' + keys);

In the code above, Object.keys(obj) returns an array of strings representing the keys of the obj object. The keys variable will now contain the following array:

['key1', 'key2', 'key3', 'key4']

The keys.length property provides the number of keys in the object, which is 4 in this case. The console.log() statement displays the result to the console.

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