[SalesForce] Visualforce still sees the old controller variable value even after update

I have a simple controller and VisualForce page as written below:

SampleCon.cls

    public with sharing class SampleCon {

    public Boolean buttonOneClicked {get; set;}

    public Boolean buttonTwoClicked {get; set;}

    public PageReference buttonOne(){

        this.buttonOneClicked = true;       
        return null;

    }

    public PageReference buttonTwo(){

        this.buttonTwoClicked = true;       
        return null;

    }

    public SampleCon(ApexPages.StandardController stdController) {
    }

    public void init() {
        this.buttonOneClicked = false;
        this.buttonTwoClicked = false;
    }
}

SampleConPage

<apex:page standardController="Account" extensions="SampleCon" action="{!init}">
<Script type="text/javascript">
    function printControllerValues(){
        console.log('Button One Clicked value is '+ '{!buttonOneClicked}');     
        console.log('Button Two Clicked value is '+ '{!buttonTwoClicked}');     
    }
    document.addEventListener("DOMContentLoaded", function(event) { 
        console.log('Button One Clicked value is '+ '{!buttonOneClicked}');     
        console.log('Button Two Clicked value is '+ '{!buttonTwoClicked}');     
    });       
</Script>
<apex:form >
    <apex:outputPanel id="first">
    <apex:pageBlock >
        <apex:pageBlockButtons >
            <apex:commandButton action="{!buttonOne}" value="Button One" onComplete="printControllerValues(); return false;"/>
            <apex:commandButton action="{!buttontwo}" value="Button Two" onComplete="printControllerValues(); return false;"/>
        </apex:pageBlockButtons>
        <apex:pageBlockSection >
        </apex:pageBlockSection>    
    </apex:pageBlock>
    </apex:outputPanel>
</apex:form>

Problem Description:
I have two boolean variables in controller to check which button was clicked. As soon as the button is clicked I change the value to true and print the values from Javascript function using onComplete function.
But every time, I see that buttonOneClicked and buttonTwoClicked variables are still showing false

Can somebody help on what I am doing wrong here?