how to set sparse index in array of objects in javascript? [duplicate]

I want to set for example :

myarray[3922] = {
    name : 'john'
    family : 'doe'
}

which did not make null indices like this :

myarray[0] = null

myarray[1] = null

.

.

.

myarray[3920] = null

myarray[3921] = null

myarray[3922 = { name : 'john' family : 'doe' }

so that I can have direct access to myarray[3922].name .

I use these for saving in localStorage, like this: how to set value to some desired index of array in javascript?

thanks in advance