I am doing a java script application that calculates Miles driven / gallons used and gallons used* price per gallon. I have two problems:
1) when I enter all the values price per gallon adds a another zero automatically. For example 40, becomes 400.
2) I am looking to write the result of both calculations underneath the button.
If anyone can give me guidance or help I would really appreciate it.
<!DOCTYPE
<html>
<head>
<meta charset="utf-8">
<title> MPG application </title>
<script>
var $ = function(id) {
return document.getElementById(id);
}
/* the user entries will be parsed floats and a if
statment is checking to see if the person enters not #*/
var calculateMpg = function () {
var miles = parseFloat($("miles").value); //alert(miles);
var gallons = parseFloat($("gallons").value);
var costGallon = document.getElementById("costGallon").value;
if (isNaN(miles) || isNaN(gallons)) {
alert("enter a valid number");
}
else {
var mpg = miles/gallons;
var costGallon = gallons*costGallon;
$("costGallon").value=costGallon.toFixed(2);
//alert("your total is" +mpg );
alert("your total new is " + costGallon);
//cost of trip = gallons used * price per gallon
}
}
//write to the page
window.onload = function () {
$("calculate").onclick = calculateMpg;
//focues means brings the window to the front
$("costGallon").focus();
}
</script>
</head>
<section>
<body>
<h1> calculate mPG </h1>
<p>Enter the information below</p>
<label for="miles">Miles Driven: </label>
<!--the code under gives a form box of text-->
<input type="text" id="miles"> <br><br>
<label for = "gallons"> Gallons of gas used :</label>
<input = "text" id="gallons"><br><br>
<label for = "costGallon"> Price per Gallon: </label>
<input = "text" id="costGallon" ><br><br>
<label> </label>
<input type = "button" id = "calculate" value = "Calculate MPG and cost of the trip">
<!-- So here I want to say your mpg is and then call mpg. which I thought I did in the top abobe window.onload -->
<p style="color: red"> Your mpg is: <span id = "totalMpg"> </span>
</section>
</body>
</html>
Can you give me an example of where it does that? I copy pasted your code and for me it gives the correct values. From what I understand the only thing you are writting into the cost per gallon field is the gallons used times the price per gallon. An that seems to be working fine.
If you can provide me with a example calculation you want to achive i'd be happy to help.
On another note, i suggest not using the same variable again in line 27 that you used to hold the DOM object of the input field. Also toFixed does not change the variable you used it on but return a new variable so instead remove that in line 28 and have line 27 look something like this:
var newVarNameIsBoss = (gallons*costGallon).toFixed(2);
Hope this helps
revised code
<!DOCTYPE html> <!-- scorrect doctype-->
<html>
<head>
<meta charset="utf-8">
<title> MPG application </title>
<script>
var $ = function(id) {
return document.getElementById(id);
};//remember that a var decleration always ends with a ; even if it's a function
/* the user entries will be parsed floats and a if
statment is checking to see if the person enters not #*/
var calculateMpg = function () {
var miles = parseFloat($("miles").value), //alert(miles);
gallons = parseFloat($("gallons").value),
costGallon = document.getElementById("costGallon").value,
mpg,totalCost;
if (isNaN(miles) || isNaN(gallons)) {
alert("enter a valid number");
} else {
mpg = miles/gallons;
totalCost = (gallons*costGallon).toFixed(2);
costGallon.value=totalCost;
alert("your total new is " + totalCost);
$('totalMpg').innerHTML = String(mpg.toFixed(2)) + " Miles per Gallon";
}
};//remember that a var decleration always ends with a ; even if it's a function
//write to the page
window.onload = function () {
$("calculate").onclick = calculateMpg;
//focues means brings the window to the front
$("costGallon").focus();
};//remember that a var decleration always ends with a ; even if it's a function
</script>
</head>
<body>
<section> <!-- section bellow the body tag-->
<h1> calculate mPG </h1>
<p>Enter the information below</p>
<label for="miles">Miles Driven: </label>
<!--the code under gives a form box of text-->
<input type="text" id="miles"> <br/><br/>
<label for = "gallons"> Gallons of gas used :</label>
<input = "text" id="gallons"><br/><br/>
<label for = "costGallon"> Price per Gallon: </label>
<input = "text" id="costGallon" ><br/><br/>
<label> </label>
<input type = "button" id = "calculate" value = "Calculate MPG and cost of the trip">
<!-- So here I want to say your mpg is and then call mpg. which I thought I did in the top abobe window.onload -->
<p style="color: red"> Your mpg is: <span id = "totalMpg"> </span></p><!--closing p tag here-->
</section>
</body>
</html>
Related
I’m trying to get the computer to take an input from the HTML and add and multiply some number to it in Javascript. I’m from python and the variable system in Javascript makes no sense to me, so can someone please lmk what to do?
<div class = "text">How much energy do you use?</div>
<input id = "q1" type = "text" placeholder = "# of KilaWatts"></input>
<button type="button" onclick="getInputValue();">Submit</button>
<!-- Multiply InputValue by 3 and Add 2 —->
I tried to do something with parseInt, and parseString, but it didn’t work as it would just not run.
try this, first query input value then calculate your desire numbers then alert the user,
like this <!-- Multiply InputValue by 3 and Add 2 —->
function getInputValue() {
const inputVal = document.getElementById("q1").value; //query input value
const calculatedValue = ((inputVal *3) +2); // first multiply input value with 3
// then add 2
alert(calculatedValue); // show the calculated value through an alert
};
It's not that hard. try to play with the below code. Cheers!!
<html>
<body>
<label for="insertValue">Enter Your Value:</label>
<input type="text" id="insertValue">
<button onclick="Multiply()">Multiply</button> <!-- Calling to the JS function on button click -->
<p id="answer"></p>
<!-- Always link or write your js Scripts before closing the <body> tag -->
<script>
function Multiply() {
let value = document.getElementById("insertValue").value; //get the inserted Value from <input> text box
let answer = 0;
//Your Multiplication
answer = value * 2 * 3;
//Display answer in the <p> tag and it id ="answer"
document.getElementById("answer").innerText = "Your Answer is: "+ answer;
}
</script>
</body>
</html>
Easy (to understand) Solution:
<div class="text">How much energy do you use?</div>
<input id="q1" type="text" placeholder="# of KilaWatts"></input>
<button type="button" onclick="getInputValue();">Submit</button>
<br>
<output id="a1"></output>
<script>
var input = document.getElementById("q1");
var output = document.getElementById("a1");
function getInputValue() {
output.textContent = (input.value * 3) + 2;
}
</script>
I made this calculator http://fernandor80.neocities.org/plancalc/tomx2.html
and it always returns Nan, but once you reload it (with the previously entered inputs), it works...
I've been looking around but I can not figure it out... So I'm here because I really want to get it to work.
here is the code to it:
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Plant Calc V1.2</title>
<link rel="stylesheet" href="main.css">
</head>
<body>
<main>
<form name="plantrow" method=POST>
<h1>How many trays per round?</h1>
<input type="text" id="ppr">
<br>
<h1>How many rows (6,10,12)?</h1>
<input type="text" id="bed">
<input type="button" id="firstcalc" value="go!" onClick="row()">
</form>
<br>
<h2>Trays per row::</h2>
<h1 id="ppb"></h1>
<form name="field" method=POST>
<h1>Total rows in the field??</h1>
<input type="text" id="totalb">
<input type="button" id="secondcalc" value="go!" onClick="total()">
</form>
<h1>You need:::</h1>
<h1 id="totalp"></h1>
<h1>trays</h1>
<div id="bins">
45 count bins<h2 id="bin45"></h2>
90 count bins<h2 id="bin90"></h2>
</div>
<form name="nowplants" method=POST>
<h1> How much plant you have now(trays)???</h1>
<input type="text" id="nowp">
<input type="button" id="thirdcalc" value="go" onClick="now()">
</form>
<h1>You can plant ::</h1>
<h1 id="nowb"></h1>
<h1>rows</h1>
</main>
<script language="JavaScript">
var ppr = parseFloat(document.getElementById("ppr").value);
var bed = parseFloat(document.getElementById("bed").value);
var ppb = ppr/bed ;
var totalb = parseFloat(document.getElementById("totalb").value);
var totalp = totalb * ppb;
var bin45 = totalp/45 ;
var bin90 = totalp/90 ;
var nowp = document.getElementById("nowp").value;
var nowb = nowp/ppb ;
function row(){
document.getElementById("ppb").innerHTML = ppb;
}
function total(){
document.getElementById("totalp").innerHTML = totalp;
document.getElementById("bin45").innerHTML = bin45;
document.getElementById("bin90").innerHTML = bin90;
}
function now(){
document.getElementById("nowb").innerHTML = nowb;
}
</script>
</body>
</html>
Also it doesnt work on mobile devices..I made a pure javascript prompt based calculator for that, but for the purpose of learning i would like some pointers.
I really feel bad about asking a question thats been answered hundreds of times. Sorry, I just had to..
the values of ppr, bed, and ppb are calculated when the page first loads. Thus it's a NaN.
You should consider move at least the data retrieval and calculation inside function row().
One simple way to debug issue like this, if you don't use any IDE, it to press f12 in your browser and open dev mode where you can set break point and check the current value of your variables.
You have dependency over other variable in every function. Instead of using global variables, you can access value in each function.
function row() {
var ppr = parseFloat(document.getElementById("ppr").value);
var bed = parseFloat(document.getElementById("bed").value);
var ppb = ppr / bed;
document.getElementById("ppb").innerHTML = ppb;
}
function total() {
var ppr = parseFloat(document.getElementById("ppr").value);
var bed = parseFloat(document.getElementById("bed").value);
var ppb = ppr / bed;
var totalb = parseFloat(document.getElementById("totalb").value);
var totalp = totalb * ppb;
var bin45 = totalp / 45;
var bin90 = totalp / 90;
document.getElementById("totalp").innerHTML = totalp;
document.getElementById("bin45").innerHTML = bin45;
document.getElementById("bin90").innerHTML = bin90;
}
function now() {
var ppr = parseFloat(document.getElementById("ppr").value);
var bed = parseFloat(document.getElementById("bed").value);
var ppb = ppr / bed;
var totalb = parseFloat(document.getElementById("totalb").value);
var totalp = totalb * ppb;
var bin45 = totalp / 45;
var bin90 = totalp / 90;
var nowp = document.getElementById("nowp").value;
var nowb = nowp / ppb;
document.getElementById("nowb").innerHTML = nowb;
}
<main>
<form name="plantrow" method=POST>
<h1>How many trays per round?</h1>
<input type="text" id="ppr">
<br>
<h1>How many rows (6,10,12)?</h1>
<input type="text" id="bed">
<input type="button" id="firstcalc" value="go!" onClick="row()">
</form>
<br>
<h2>Trays per row::</h2>
<h1 id="ppb"></h1>
<form name="field" method=POST>
<h1>Total rows in the field??</h1>
<input type="text" id="totalb">
<input type="button" id="secondcalc" value="go!" onClick="total()">
</form>
<h1>You need:::</h1>
<h1 id="totalp"></h1>
<h1>trays</h1>
<div id="bins">
45 count bins
<h2 id="bin45"></h2>
90 count bins
<h2 id="bin90"></h2>
</div>
<form name="nowplants" method=POST>
<h1> How much plant you have now(trays)???</h1>
<input type="text" id="nowp">
<input type="button" id="thirdcalc" value="go" onClick="now()">
</form>
<h1>You can plant ::</h1>
<h1 id="nowb"></h1>
<h1>rows</h1>
</main>
It will always NaN because your call values of ppr, bed, and ppb when just first page loaded ! At that page loaded time ,you didn't have any value so NaN getting.So when you click ,you should call that value again ,make it function to call values will be more better...
here I push init() to get value onclick
<script type="text/javascript">
var ppr,bed,ppb,totalp,totalb,bin45,bin90,nowb,nowb;
function init(){
ppr = parseFloat(document.getElementById("ppr").value);
bed = parseFloat(document.getElementById("bed").value);
ppb = ppr/bed ;
totalb = parseFloat(document.getElementById("totalb").value);
totalp = totalb * ppb;
bin45 = totalp/45 ;
bin90 = totalp/90 ;
nowp = document.getElementById("nowp").value;
nowb = nowp/ppb ;
}
function row(){
init();
document.getElementById("ppb").innerHTML = ppb;
}
</script>
I have studied java and php for many years and recently just started developing in JavaScript as well. Anyway a fairly noob question but can anyone work out why this application isn't showing displaying the interest when the button is clicked? I have been using w3schools website to learn from.
code:
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Interest Calculator</title>
</head>
<body>
<fieldset>
<legend>Interest Calculator</legend>
Enter amount: <input type="text" id="amount" ><br><br>
Interest rate: <input type="text" id="interest"><br><br>
Enter years: <input type="text" id="years"><br><br>
<button onclick="calculate()">Calculate</button>
</fieldset>
<p id="sum"></p>
<script>
function calculate(){
var amount = document.getElementById("amount").value;
var rate = document.getElementById("interest").value;
var years = document.getElementById("years").value;
var sum = amount(1+rate)^years;
var message = "Your total return will be: " + sum;
document.getElementById("sum").innerHTML = message;
}
</script>
</body>
</html>
Many thanks,
Adam
You need to explicitly specify *. It is not normal for 5(3) = 15 in JavaScript or any programming language. You need to explicitly specify 5*(3):
var sum = amount*(1+rate)^years;
Working Code
<fieldset>
<legend>Interest Calculator</legend>
Enter amount: <input type="text" id="amount" ><br><br>
Interest rate: <input type="text" id="interest"><br><br>
Enter years: <input type="text" id="years"><br><br>
<button onclick="calculate()">Calculate</button>
</fieldset>
<p id="sum"></p>
<script>
function calculate(){
var amount = document.getElementById("amount").value;
var rate = document.getElementById("interest").value;
var years = document.getElementById("years").value;
var sum = amount*(1+rate)^years;
var message = "Your total return will be: " + sum;
document.getElementById("sum").innerHTML = message;
}
</script>
Fiddle: http://jsbin.com/lovevazaxe
The OP uses the ^ operator and presumably wants to use the power-of operator.
In javascript the ^ operator refers to bitwise XOR - I don't think that's what the OP wants.
Instead, the power-of operation is done with the Math.pow() function.
So replace var sum = amount(1+rate)^years; with
var sum = Math.pow(amount*(1+rate),years)
Hi I am NewBee in Javascript. This is my second week.
Below is the code that has a form with three input fields.
The relationship of the fields is:
the second field is twice the value of the first field
the third field is the square of the first field
I have managed to do the above but i am not able to do the below :
If a user enters a value in the second or third field, the script should calculate the appropriate value in the other fields. Currently the code works well ONLY if I enter the value in the first field.
I hope I explained well in other words : how do I enter say 144 in the last textbox and the other 2 textboxes show 12 and 24 respectively. Or If I enter 24 first and first and the third text boxes show 12 and 144.
Thanks
Vipul
<html>
<head>
<script>
window.onload = init;
function init() {
var button = document.getElementById("usrButton");
button.onclick = save;
onkeyup = doMath;
function doMath(){
var base = document.getElementById("base").value;
var baseNumber_timesTwo = document.getElementById("baseNumber_timesTwo").value = (base*2);
var baseNumber_square = document.getElementById("baseNumber_square").value = (base*base) ;
}
}
</script>
</head>
<body>
<form>
<input type="text" name="base" id="base" onkeyup= "doMath()">
<br><br>
<input type="text" name="baseNumber_timesTwo" id="baseNumber_timesTwo" onkeyup= doMath()>
<br><br>
<input type="text" name="baseNumber_square" id="baseNumber_square" onkeyup= doMath()> <br><br>
</form>
</body>
</html>
take a look at the code below:
<html>
<head>
<script>
window.onload = init;
var init = function(){
var button = document.getElementById("usrButton");
button.onclick = save;
onkeyup = doMath;
}
var doMathbase = function(){
console.log('here');
var base = document.getElementById("base").value;
var baseNumber_timesTwo = document.getElementById("baseNumber_timesTwo").value = (base*2);
var baseNumber_square = document.getElementById("baseNumber_square").value = (base*base) ;
}
var doMathBase2Time = function(){
var baseNumber_timesTwo = document.getElementById("baseNumber_timesTwo").value;
var base = document.getElementById("base").value = (baseNumber_timesTwo/2);
var baseNumber_square = document.getElementById("baseNumber_square").value = (base*base) ;
}
</script>
</head>
<body>
<form>
<input type="text" name="base" id="base" onkeyup= "doMathbase()">
<br><br>
<input type="text" name="baseNumber_timesTwo" id="baseNumber_timesTwo" onkeyup= "doMathBase2Time()">
<br><br>
<input type="text" name="baseNumber_square" id="baseNumber_square" onkeyup= "doMathBaseSquare()">
<br><br>
</form>
</body>
You need to bind another function to the second and third field. I did it to the second. Now if you entered a number in the second field it return the 'base' number and the square of the base.
Try do it for the third :)
This should fit your needs:
Fiddle
//declaring those earlier saves you to get those by ID every
//time you call "doMath()" or something else
var base = document.getElementById("base");
var baseNumber_timesTwo = document.getElementById("baseNumber_timesTwo");
var baseNumber_square = document.getElementById("baseNumber_square");
function clearUp() {
base.value = "";
baseNumber_timesTwo.value = "";
baseNumber_square.value = "";
}
function doMath() {
//check which of the fields was filled
if(baseNumber_timesTwo.value){
base.value = baseNumber_timesTwo.value / 2;
}
if(baseNumber_square.value){
base.value = Math.sqrt(baseNumber_square.value);
}
//fill other fields according to that
baseNumber_timesTwo.value = (base.value*2);
baseNumber_square.value = (base.value*base.value) ;
}
As you see: There is no need to write more than one arithmetic function if you make sure that only one value is given at the time of evaluation (this is achieved by the cleanUp()
method)
However there are still some flaws in this solution! Since you are a js beginner I would suggest you to read the code and think about possible solutions for those problems as a little exercise :-)
- You cannot enter a 2 (or more) digit number in any field, why not? What do you have to change in order to allow such numbers as input?
- Why is it better (in this case!) to set the values to " " instead of '0' in the cleanUp function? Why does the code break when you try using '0' instead of "" ?
- Why does doMath() only check for values in the last two field (baseNumber_timesTwo and baseNumber_square) while ignoring the 'base' field?
Greetings, Tim
Sounds easy probably, but not for a beginner programmer :)
I have a simple 3 field form with a submit button and a clear button. This is for a homework assignment, and we have been tasked to get the "Clear Fields" button to work properly. Here are more specific instructions:
"Add the JavaScript code for an anonymous function that's stored in a variable named clear. The function should clear the text boxes by using the $ function to get a Textbox object for each text box and then setting the value property of the textbox to an empty string. Then, add a statement in the onload event handler that attaches the clear function to the click event of the Clear Entries button."
I was able to add the statement to the onload event handler:
window.onload = function () {
$("calculate").onclick = calculateMpg;
$("miles").focus();
$("clear").onclick = clear;
}
But it is the other part I am having problems with.
Add the JavaScript code for an anonymous function that's stored in a variable named clear:
var clear = function () {
Object.Method
}
Here is my full code so far:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Calculate MPG</title>
<link rel="stylesheet" href="mpg.css">
<script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
<script>
var $ = function (id) {
return document.getElementById(id);
}
var calculateMpg = function () {
var miles = parseFloat($("miles").value);
var gallons = parseFloat($("gallons").value);
if (isNaN(miles)) {
alert("Miles: This must be a numeric value.");}
else if (miles <0) {
alert("Miles: This number must be greater than 0.");}
else if (isNaN(gallons)) {
alert("Gallons: This must be a numeric value.");}
else if (gallons <0) {
alert("Gallons: This number must be greater than 0.");}
else {
var mpg = miles / gallons;
$("mpg").value = mpg.toFixed(1);
}
}
var clear = function () {
miles.Text = String.Empty
}
window.onload = function () {
$("calculate").onclick = calculateMpg;
$("miles").focus();
$("clear").onclick = clear;
}
</script>
</head>
<body>
<section>
<h1>Calculate Miles Per Gallon</h1>
<label for="miles">Miles Driven:</label>
<input type="text" id="miles"><br>
<label for="gallons">Gallons of Gas Used:</label>
<input type="text" id="gallons"><br>
<label for="mpg">Miles Per Gallon</label>
<input type="text" id="mpg" disabled><br>
<label> </label>
<input type="button" id="calculate" value="Calculate MPG"><br>
<label> </label>
<input type="button" id="clear" value="Clear Entries"><br>
</section>
</body>
</html>
And here is the code we were supplied with to work off of:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Calculate MPG</title>
<link rel="stylesheet" href="mpg.css">
<script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
<script>
var $ = function (id) {
return document.getElementById(id);
}
var calculateMpg = function () {
var miles = parseFloat($("miles").value);
var gallons = parseFloat($("gallons").value);
if (isNaN(miles) || isNaN(gallons)) {
alert("Both entries must be numeric");
}
else {
var mpg = miles / gallons;
$("mpg").value = mpg.toFixed(1);
}
}
window.onload = function () {
$("calculate").onclick = calculateMpg;
$("miles").focus();
}
</script>
</head>
<body>
<section>
<h1>Calculate Miles Per Gallon</h1>
<label for="miles">Miles Driven:</label>
<input type="text" id="miles"><br>
<label for="gallons">Gallons of Gas Used:</label>
<input type="text" id="gallons"><br>
<label for="mpg">Miles Per Gallon</label>
<input type="text" id="mpg" disabled><br>
<label> </label>
<input type="button" id="calculate" value="Calculate MPG"><br>
</section>
</body>
</html>
You've got several issues going on:
You're mixing Javascript and jQuery in ways that don't quite work.
jQuery's methods and objects work differently than "pure"
Javascript, so be mindful of that.
The window.onload doesn't work the way you've got it. To be
consistent, do it the jQuery way with a $(document).ready() method
instead.
You're missing the # indicator on your jQuery IDs. This is
imperative or it won't find the ID of the elements you're calling.
It looks like you're mixing VB/C# code in with your javascript, such
as the String.Empty call, etc. Those objects/methods work from the
server and not in Javascript, so that's another issue (it's been a
while since I've worked in C#, so double check me on that).
Here's my solution below. I tweaked a few things to help with what I think you're going for (such as clearing ALL fields with the "Clear" button instead of just the miles field).
I understand you're a student, so don't make it a habit of coming here and trying to find people to do your homework for you. You did provide an attempt at some code, and there were a number of issues in it, so I chose to rectify them for you and explain the reasons since there were so many. Others are not as generous, but I was a struggling student once, too, so I get it when you're banging your head against the wall. :-)
$( document ).ready( function () {
var clear = function () {
miles.value = "";
gallons.value = "";
mpg.value = "";
}
var calculateMpg = function () {
var miles = parseFloat($("#miles").val());
var gallons = parseFloat($("#gallons").val());
if (isNaN(miles)) {
alert("Miles: This must be a numeric value.");
}
else if (miles <0) {
alert("Miles: This number must be greater than 0.");
}
else if (isNaN(gallons)) {
alert("Gallons: This must be a numeric value.");
}
else if (gallons <0) {
alert("Gallons: This number must be greater than 0.");}
else {
var mpg = miles / gallons;
$("#mpg").val(mpg.toFixed(1));
}
}
$("#calculate").bind("click", calculateMpg);
$("#miles").focus();
$("#clear").bind("click", clear);
});