difference between two variables

Question

Hi I was trying to print an array variables on my console of my browser. Firstly I tried to print the below

var name = [ 'john', 'mark'];
var years = new Array(1990,1969,1948);

console.log(name[1]);
console.log(name.length);

and got the output as below

And finally I added the names instead of name as shown in below code

var names = [ 'john', 'mark'];
var years = new Array(1990,1969,1948);

console.log(names[1]);
console.log(names.length);

and output for the above code is shown in this

Can I know whats the difference between?

Answer 1

You are colliding with the built in window.name property

window.name will convert all values to their string representations by using the toString method.

Answer 2

window.name will provide the name of you current window. More info: https://www.oreilly.com/library/view/javascript-the-definitive/0596000480/re335.html

The variable name in your example is treated like it was a String, even after you tried to change it to an array.

Print the variables name and names and you will see the differences.

Output of console.log(name): "john,mark" Output of console.log(names): ["john", "mark"]

Edit: Reason was provided by @charlietfl

Answer 3

Reason:

💡 window.name

Actually when you defines a variable with var keyword and name name , you are using the window.name field of the browser DOM.

And when you defines the name with var keyword it can not override the string type and behavior of the window.name to array and your value will be saved in its as string » "john,mark"

Proof:

 console.log(window.name); { var name = [ 'john', 'mark']; console.log(window.name); console.log(name); console.log(name[1]); console.log(name.length); } 

Solution:

💡 let

If you want to have a name variable other than window.name you should use let keyword instead of var :

 { let name = [ 'john', 'mark']; console.log(name); console.log(name[1]); console.log(name.length); }