best syntax for storing an object in a variable code example

Example 1: creating an object javascript

let obj = {
// fields
  name:"value",
  num: 123,
//methods
  foo: function(){}
  
}

Example 2: js obj

var obj = {my:"sql",  nice:[69, 420]};

obj.my //returns the string "sql"
obj.nice //returns the array [69, 420]