Validation errors in javascript [duplicate]

I want to check if my application's buttons are pressed or not. The error I face is, even when the buttons are clicked all the alerts display. Attached is the code snippet, the variables are set by click of buttons.

I want the alert not to display if any of the values are selected,

var condition ; 
var clickable;     // GLOBAL VARIABLES

function clickMe1() 
{
    clickable = "Sell";
}

function clickMe2() 
{
    clickable = "Rent";
}

function condition1()
{
    condition="Excellent"
}

function condition2()
{
    condition="Good"
}

function condition3()
{
    condition="Fair"
}

function condition4()
{
    condition="New"
}



function display()    
{
    if (condition != "Excellent"||"New"||"Fair"||"Good")
    {
        alert( " Please enter the condition ");
    }
    if (clickable != "Sell"||"Rent")
    {
        alert("Please enter the Sell");
    }
    if (costSell === '')  
    {
        alert("Please select a Price ");
    }
    if ((condition === "Excellent"||"New"||"Fair"||"Good") && (clickable === "Selling"||"leasing")&&(!isNaN(costSell)))
    {
        // Do Something
    },
    error: function(data){
        console.log("not added");
    }
    });
    }
    else
    {
        alert(" price is not a number"); 
    }
}

I also tried:

if(condition !='Excellent'|| condition!='New' || condition!='Fair'|| condition!='Good')
{
    alert( " Please enter the condition ");
}
if (clickable !='Sell'||'Rent' )
{
    alert("Please enter the Sell ");