How to count the number of properties in a JavaScript object

Dec 7, 2018

Learn how to count the number of properties in a JavaScript object using Object.keys() to get an array of its enumerable keys and reading the length property.

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Use the Object.keys() method, passing the object you want to inspect, to get an array of all the (own) enumerable properties of the object.

Then calculate the length of that array by checking the length property:

const car = {
  color: 'Blue',
  brand: 'Ford',
  model: 'Fiesta'
}

Object.keys(car).length

I said enumerable properties. This means their internal enumerable flag is set to true, which is the default. Check MDN for more info on this subject.

Tagged: JavaScript · All topics

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