Question

Sorry this is obviously my first time here, I am just learning how to work in javascript. My question is this: I have some basic calculations determing a price of a service for our non-profit. t is the number of rooms * 0.81. But we have a monthly minimum of $60. So I need to know how I would factor that into the pricing function. I know it goes that “if x < 60, then 60”, just not sure how the language would be written. I will include the full js.

var listenerFieldIDs = {"roomCountID":"item4_text_1"}; //Currently the only form we are using for room count has this value set as its ID attribute.

var impactFields = ["item12_text_1","item1_text_1","item16_text_1","item18_text_1","item20_text_1"]; //Field IDs for the form that will be changed constantly.
var estimatedBottleSize = 1.5, occupancyRate = (60 / 100), collectionDuration = 365, soapOuncesRecoverable = 0.63, bottleOuncesRecoverable = 0.47,lbConversion = 0.0626, rate = 0.81;

var $ = function(id){ //Shortcut to save some typing. Instead of having to write out document.getElementById(elementID) every time I need to access an element, I can put $(elementID).property or $(elementID).method() I need more easily.
    return document.getElementById(id);
}

var updateFormField = function(id,amount){ //Updates a form field when gives the element ID and the amount.
    $(id).value = amount;
}

var updateForm = function(roomCount){ 

    // This is called when all form data needs to be updated. This is generally invoked each time a keystroke in the room count field.
    updateFormField(impactFields[0],calculateLbsOfSoap(roomCount).toFixed(2)); //Updating the first form field after calculating the total weight of soap in lbs.
    updateFormField(impactFields[1],calculateLbsOfBottles(roomCount).toFixed(2)); //Same thing as above, but bottles/amenities.
    updateFormField(impactFields[2],calculateBarsOfSoap(roomCount).toFixed(0)); //Updating the third form field after calculating the total number of distributed units.
    updateFormField(impactFields[3],calculateBottles(roomCount).toFixed(0)); //Same as above, but bottles/amenities.
    updateFormField(impactFields[4],("$" + calculatePrice(roomCount).toFixed(2))); //Updating price.
}

var listenForNumbers = function(event){ //This function is acting as a handler for when anything is entered into the field.
    updateForm($(listenerFieldIDs["roomCountID"]).value);
}

var calculateLbsOfSoap = function (rmCnt){ // Calculate the weight of soap and return the amount.
    return checkCount(rmCnt) ? 0 : ((soapOuncesRecoverable * lbConversion) * (rmCnt * occupancyRate) * collectionDuration); 
}

var calculateLbsOfBottles = function (rmCnt){ // Calculate the weight of bottled amenities and return the amount.
    return checkCount(rmCnt) ? 0 : ((bottleOuncesRecoverable * lbConversion) * (rmCnt * occupancyRate) * collectionDuration);
}

var calculateBarsOfSoap = function(rmCnt){ // Calculate how many bars are distributed if the room count is not 0.
    return checkCount(rmCnt) ? 0 : ((calculateLbsOfSoap(rmCnt) * 16) / 3);
}

var calculateBottles = function(rmCnt){ // Calculate how many bottles are distributed if the room count is not 0.
    return checkCount(rmCnt) ? 0 : (((calculateLbsOfBottles(rmCnt) * 16) / estimatedBottleSize) * (2 / 3)); 
}

var calculatePrice = function(rmCnt){

    return checkCount(rmCnt) ? 0 : (rmCnt * rate);
    }


var checkCount = function(count){ //If the count is 0  or less than 0, the number is useless so just return 0 to prevent odd results.
    return (count < 0 || count == 0) ? true : false; 
}

var initializeRealTimeCalcToForm = function(){ 



    if(window.attachEvent){
        $(listenerFieldIDs["roomCountID"]).attachEvent("onkeydown",listenForNumbers,false);
        $(listenerFieldIDs["roomCountID"]).attachEvent("onkeyup",listenForNumbers,false);
        $(listenerFieldIDs["roomCountID"]).attachEvent("onkeypress",listenForNumbers,false);
        $(listenerFieldIDs["roomCountID"]).attachEvent("onchange",listenForNumbers,false);
    } else{
    //But if NOT IE... :-D
        $(listenerFieldIDs["roomCountID"]).addEventListener("keydown",listenForNumbers,false);
        $(listenerFieldIDs["roomCountID"]).addEventListener("keyup",listenForNumbers,false);
        $(listenerFieldIDs["roomCountID"]).addEventListener("keypress",listenForNumbers,false);
        $(listenerFieldIDs["roomCountID"]).addEventListener("change",listenForNumbers,false);
    }

}

window.onload = function(){  

    initializeRealTimeCalcToForm();
}

Answer 1

If you only want to set a minimum value of 60 to the variable myvar, you can do

myvar=Math.max(60,myvar);

Edit:

Then, if you want the value returned by calculatePrice to be at least 60, use:

var calculatePrice=function(rmCnt){
    return Math.max(60,checkCount(rmCnt) ? 0 : (rmCnt * rate));
}

Note 1:

Do you know that you can declare functions like this?

function calculatePrice(rmCnt){
    return Math.max(60,checkCount(rmCnt) ? 0 : (rmCnt * rate));
}

It’s shorter and this way you can call the function before declaring it!

Note 2:

If you want that value to be at least 60, I don’t understand the following code:

checkCount(rmCnt) ? 0

Why 0?