get length of an array javascript

1var numbers = [1, 2, 3, 4, 5];
2var length = numbers.length;
3for (var i = 0; i < length; i++) {
4  numbers[i] *= 2;
5}
6// numbers is now [2, 4, 6, 8, 10]
7

1var arr = [10,20,30,40,50]; //An Array is defined with 5 instances
2
3var len= arr.length;  //Now arr.length returns 5.Basically, len=5.
4console.log(len); //gives 5
5console.log(arr.length); //also gives 5

1const { BrowserWindow } = require('electron')
2
3const win = new BrowserWindow()
4win.webContents.openDevTools()
5