Jump to content

Accessing Arrays with Named Indexes


dgvirtual
 Share

Recommended Posts

I was fiddling with „Accessing Arrays with Named Indexes“ section examples of the Javascript tutorial and run into a situation I cannot explain. 

In short, I create an array 'person', then add elements to the array by index, and then add a third element by name. According to the tutorial, this should convert the array to an object (see here: https://www.w3schools.com/js/js_mistakes.asp) . Instead, after this I can access the variable 'person' as both an array (with two elements) and an object (or rather, a person.age property of the object). typeof 'person' reports: object.

var person = [];
person[0] = "John";
person[1] = "Doe";
person["age"] = 46;

Here is a link to the full test: https://www.w3schools.com/code/tryit.asp?filename=GHWE7BWHX1GH

Could someone explain what is happening here?

Link to comment
Share on other sites

3 things to answer your questions

Arrays strictly only have numerical indexes.

Adding a string index converts the array to a generic object.

You can access an object's properties through square bracket [] method, just like an array.

Link to comment
Share on other sites

OK, thank you, I see that adding this code:

const entries = Object.entries(person)

document.getElementById("demo3").innerHTML =
"entries: " + entries;

to my post results in printing all the object properties and values on the screen.

The only thing that I cannot understand is why the `person.length` reports 2 when the length of the object is actually 3 (2 does not change if I comment out the line that ads the third property and converts the array to an object).

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...