how to give variable type in javascript code example

Example 1: how to define variable in javascript

var <variable-name>;

var <variable-name> = <value>;

Example 2: var = {} js

//An array is a type of object intended to be only assigned numeric keys
var tmp = []; // or: var tmp = {}
tmp.one = 1;
JSON.stringify(tmp);

// array:
'[]'

// object:
'{"one":1}'