how to add a variable at last inside a object in javascript code example

Example 1: ad data to js object

//Consider the following example object literal:
var myObject = {
    sProp: 'some string value',
    numProp: 2,
    bProp: false
};

//You can use dot syntax to add a new property to it as follows:
myObject.prop2 = 'data here';

//Modify a Property of an Object Literal
//The process for modifying a property is essentially the same. 
//Here we will assign a new value to the sProp property shown in the 
//original myObject definition above:
myObject.sProp = 'A new string value for our original string property';

//Read Current Value of Object Property
//The following demonstrates how to access a property of an object literal:
alert(myObject.sProp) // display myObject.sProp value in alert
var val = myObject.sProp; // assign myObject.sProp to variable

Example 2: javascript object string property

// Also useful for dynamic strings, e.g. `thing-${variable}`
myObject['thing'] = true;