Javascript max and min not working - javascript

I am trying to create a page that lets the user enter three numbers, and have the max and min values printed below from the input. I've used both the Math.max/min functions and also tried an if statement but When I click submit nothing shows up. Some insight would be greatly appreciated, thanks!
function max() {
var x = document.getElementById("num1").value;
var y = document.getElementById("num2").value;
var z = document.getElementById("num3").value;
var maximum = Math.max(parseInt(x), parseInt(y), parseInt(z));
document.getElementById("max").innerHTML= maximum;
}
function min() {
var x = parseInt(document.getElementById("num1").value);
var y = parseInt(document.getElementById("num2").value);
var z = parseInt(document.getElementById("num3").value);
document.getElementById("min").innerHTML = Math.min(x,y,z);
}
And here is my html
<p>Enter First Number:</p>
<input type="text" name = "number1" id="num1"><br>
<p>Enter Second Number</p>
<input type="text" name = "number2" id="num2"><br>
<p>Enter third number</p>
<input type="text" name = "number3" id="num3"><br>
<input type="submit" value="Submit" onclick="max(); min(); "><br />
<p>Max =</p><p id ="max"></p><br />
<p>Min =</p><p id ="min"></p><br />

replace <input type="submit"/> to <button type="submit" value="" onclick="minmax();">Submit</button>
and add JS function:
function minmax() {
min();
max();
}

Your problem seems related to how you are attaching your event.
It works OK when I use:
document.querySelector( '[type="submit"]' ).addEventListener( 'click', function() {
max();
min();
}, false );
http://jsfiddle.net/yemxrmqq/

You just need to change the tag related to the button, instead of:
<input type="submit" value="Submit" onclick="max(); min(); "><br />
just put:
<button type="submit" value="Submit" onclick="max(); min()">Click</button><br />

None of the answers here tell you why your code didn't work.
Identifiers in inline listeners are first resolved as properties of the element on which they are placed. Input elements have a default max attribute, so within an inline listener, the identifier max will reference the input's max property. Hence in any document:
<input onclick="console.log(max)">
shows '' (i.e. empty string).
So you can either change the names of the functions to something more meaningful, or change the context from which they are called so that the identifiers aren't resolved on the element, and the OP code works. e.g.
<input type="submit" value="Submit" onclick="callBoth()">
and
function callBoth() {
max();
min();
}
Incidentally, an input type submit outside a form is just a button, so you should use:
<input type="button" ...>

Related

Temperature Converter is giving me NaN

I need to make a temperature converter using forms and it has to have the ok button display the information and a clear button to clear all information.
This is what I have tried to do but it gives me NaN
function temperatureConverter(valNum) {
valNum = parseFloat(valNum);
document.getElementById("outputCelcius").innerHTML=(valNum-32)/1.8;
}
<h2>Temperature Converter</h2>
Ok now my issue is that I need everything cleared even the Celsius data but I can't find a way for it to work
<p>Type a value in the Fahrenheit field to convert te value to Celsius:</p>
<p>
<label>Fahrenheit</label>
<input id="inputFahrenheit" type="text" placeholder="Fahrenheit">
<input id= "button1" type= "button" value= "OK" onclick="temperatureConverter(this.value)">
<input id= "reset1" type= "reset" value= "Clear" onclick="temperatureConverter">
</p>
<p>Celcius: <span id="outputCelcius"></span></p>
Your code is not working because in your #button1 you wrote:
onclick="temperatureConverter(this.value)"
where this is not #inputFahrenheit but #button1. Therefore this.value actually equals to "OK".
To fix your problem, you need to change your temperatureConverter function to get value of #inputFahrenheit instead of using onclick="temperatureConverter(this.value)".
Similar situation happens in your #reset1, therefore your reset input will not work as well. You need to apply the same concept into your reset function, which I suggest to create a new function dedicated just for that.
Generally, it is not encouraged to use the same function to perform completely different actions.
function temperatureConverter(){
var input = document.getElementById('inputFahrenheit');
var value = input.value;
value = parseFloat(value);
var output = document.getElementById('outputCelcius');
output.innerHTML = (value - 32)/1.8;
}
function resetTemperature(){
/* clear the temperature */
console.log('clear');
}
<h2>Temperature Converter</h2>
<p>Type a value in the Fahrenheit field to convert te value to Celsius:</p>
<p>
<label>Fahrenheit</label>
<input id="inputFahrenheit" type="text" placeholder="Fahrenheit">
<input id= "button1" type= "button" value= "OK" onclick="temperatureConverter()">
<input id= "reset1" type= "reset" value= "Clear" onclick="resetTemperature()">
</p>
<p>Celcius: <span id="outputCelcius"></span></p>
Here is the basics needed to get your code working. Basically it is simply just changing what value is passed to the temperatureConverter function. Before you were passing it the value of the button that was being clicked, not the value of the input element you were trying to read. Also, I'm unsure on this one as I didn't look it up, but the reset element wasn't working for me until I put your items inside of a <form> element.
function temperatureConverter(valNum) {
valNum = parseFloat(valNum);
document.getElementById("outputCelcius").innerHTML=(valNum-32)/1.8;
}
<h2>Temperature Converter</h2>
<p>Type a value in the Fahrenheit field to convert te value to Celsius:</p>
<form>
<p>
<label>Fahrenheit</label>
<input id="inputFahrenheit" type="text" placeholder="Fahrenheit">
<input id= "button1" type= "button" value= "OK" onclick="temperatureConverter(document.querySelector('#inputFahrenheit').value)">
<input id= "reset1" type= "reset" value= "Clear">
</p>
</form>
<p>Celcius: <span id="outputCelcius"></span></p>
Please note that most of the time, people don't like putting the event listener in the on[event] attributes, and many developers will prefer that you do something more like this:
// () => {} is something called Arrow function notation, if you didn't know it already.
document.addEventListener('DOMContentLoaded', () => {
function updateOutput(value) {
// make sure you do some checking to avoid XSS attacks.
document.querySelector('#output').innerHTML = value;
}
// keeps the form from submitting since we don't have an actual form handler and this is all front-end
document.querySelector('#converterForm').addEventListener('submit',(e)=>{
e.preventDefault();
});
document.querySelector('#convert').addEventListener('click', () => {
updateOutput(convertToCelsius(document.querySelector('#fahrenheit').value));
});
});
function convertToCelsius(f) {
if(typeof f == 'string') f = parseFloat(f, 10);
if(isNaN(f)) {
throw new Error('Invalid parameter passed to function convertToCelsius');
}
return (f-32) * 5 / 9;
}
<form id="converterForm" action="/">
<input type="number" id="fahrenheit" placeholder="Fahrenheit value">
<input type="button" id="convert" value="Convert to Celsius">
<input type="reset" value="Clear">
<div id="output">
</div>
</form>
Other than that, a good way to check why a function isn't working is to use console.log in your code and then check the Javascript browser (in Chrome you can get to it by hitting ctrl+shift+j, in Firefox I believe it's ctrl+shift+i).
can't see you using any form.
your function,
function temperatureConverter(valNum) {
valNum = parseFloat(valNum);
document.getElementById("outputCelcius").innerHTML=(valNum-32)/1.8;
}
then,
<form id="tempConverter">
Convert: <input type="text" id="unit" name="converter" />
<input
type="button"
value="Submit"
onclick="temperatureConverter(document.getElementById('unit').value);"
/>
</form>
<p>Celcius: <span id="outputCelcius"></span></p>
apparently, if you console the value, you were obviously sending "OK" as param to the function(not the value of input field) which is NAN.

jquery - copy value of input from one form to another (form and input named the same)

I would like to copy the value from an input in one form to the value of an input(with the same name) of the next form down. The forms and inputs are named the same. All it needs to do is copy the value of the title input to the title input one form down.
<form>
<input name="file" value="1.xml">
<input name="title" id="title" value="Smith">
<input type="submit" id="copy-down" value="copy">
</form>
<form>
<input name="file" value="2.xml">
<input name="title" id="title" value="Anderson">
<input type="submit" id="copy-down" value="copy">
</form>
etc...
In this case when the top "copy" button is clicked I would like jquery to overwrite Anderson with Smith.
$('#title').attr('value'));
Gives me Smith but I'm not sure what to do with that value once I have it.
Change HTML to this:
<form>
<input name="file" value="1.xml">
<input name="title" id="title1" value="Smith">
<input type="submit" id="copy-down1" value="copy">
</form>
<form>
<input name="file" value="2.xml">
<input name="title" id="title2" value="Anderson">
<input type="submit" id="copy-down2" value="copy">
</form>
Javascript:
function copyHandler() {
var copyVal = document.getElementById("title1").value;
var replaceInput = document.getElementById("title2");
replaceInput.value = copyVal;
}
document.getElementById("copy-down1").onclick = function(){
copyHandler();
return false;
}
Some notes:
This is so straightforward in vanilla javascript that I didn't add the jQuery code.
You should never assign multiple elements to the same ID, class or name can be used for that purpose.
The return false; portion of the onclick function is necessary so that the form doesn't reload when you click your submit button.
Let me know if you have any questions.
you can try
$(document).ready(function(){
$('form').on('submit', function(e){
e.preventDefault();
var GetNameAttr = $(this).find('input:nth-child(2)').attr('name');
var GetTitleValue = $(this).find('input:nth-child(2)').val();
var NextFormNameAttr = $(this).next('form').find('input:nth-child(2)').attr('name');
if(NextFormNameAttr == GetNameAttr){
$(this).next('form').find('input:nth-child(2)').val(GetTitleValue );
}
});
});
Note: this code will change the second input value in next form with
the second input value of form you click if the name is same .. you
can do the same thing with the first input by using :nth-child(1)
Demo here
if your forms dynamically generated use
$('body').on('submit','form', function(e){
instead of
$('form').on('submit', function(e){
for simple use I create a function for that
function changeNextValue(el , i){
var GetNameAttr1 = el.find('input:nth-child('+ i +')').attr('name');
var GetTitleValue1 = el.find('input:nth-child('+ i +')').val();
var NextFormNameAttr1 = el.next('form').find('input:nth-child('+ i +')').attr('name');
if(NextFormNameAttr1 == GetNameAttr1){
el.next('form').find('input:nth-child('+ i +')').val(GetTitleValue1);
}
}
use it like this
changeNextValue($(this) , nth-child of input 1 or 2);
// for first input
changeNextValue($(this) , 1);
// for second input
changeNextValue($(this) , 2);
Working Demo

html sending parameters to function from id

I'm an absolute beginner and tried to find similar questions but couldn't. Apologies if this has been answered previously.
In my assignment we need to create a form with 2 text fields and 1 button. The fields are for height and width and the idea is that onclick on the button will send the 2 parameters to a function that will change the height + width attributes for a photo. I know I'm doing something wrong because the picture simply disappears. Ideas? Thanks!
<html>
<head>
<script>
function borderResize(height1, width1)
{
document.getElementById('Amos').height = height1;
document.getElementById('Amos').width = width1;
}
</script>
</head>
<body>
<img src="Amos.jpg" id="Amos" />
<form>
<input type="text" id="height" placeholder="Height" />
<input type="text" id="width" placeholder="Width" />
<input type="button" value="click!" onclick="borderResize('height.value', 'width.value')"/>
</form>
</body>
</html>
When you write
onclick="borderResize('height.value', 'width.value')"
in means that on click borderResize function will be invoked with two string arguments, literally strings "height.value" and "width.value". In your case you want something like this
onclick="borderResize(document.getElementById('height').value, document.getElementById('width').value)"
In above case you are selecting element from DOM using getElementById method and then read its value property.
You should learn to use addEventListener(), I would recommend you not to use ugly inline click handler.
The EventTarget.addEventListener() method registers the specified listener on the EventTarget it's called on.
Here is an example with your code.
window.onload = function() {
document.getElementById('button').addEventListener('click', borderResize, true);
}
function borderResize() {
document.getElementById('Amos').height = document.getElementById('height').value;
document.getElementById('Amos').width = document.getElementById('width').value;
}
<img src="https://fbcdn-profile-a.akamaihd.net/hprofile-ak-xpf1/v/t1.0-1/s200x200/11034289_10152822971918167_2916173497205137007_n.jpg?oh=71de7a46a75a946cf1d76e5ab10c1cdc&oe=55889977&__gda__=1434173455_6127f174627ed6014c84e562f47bc44c" id="Amos" />
<input type="text" id="height" placeholder="Height" />
<input type="text" id="width" placeholder="Width" />
<input type="button" id="button" value="click!" />
However as for your immediate problem you can use
onclick="borderResize(document.getElementById('height').value, document.getElementById('width').value)"
onclick="borderResize('height.value', 'width.value')"
here you pass to borderResize strings: 'height.value', 'width.value'.
You may get value of input from function:
function borderResize(height1, width1)
{
document.getElementById('Amos').height = document.getElementById('height').value;
document.getElementById('Amos').width = document.getElementById('width').value;
}

AJAX function not being called with button onclick function

I have a simple form with 2 input fields and one button. When the button is clicked, the value of the 2 input fields should be sent to the AJAX function to be handled in a servlet. For some reason, the servlet is not being reached. Can anyone see why? I have an almost identical method working with a different form, and I can't see why this one isn't working.
Here is the HTML form code:
<div id="addCourses" class="hidden" align="center" >
<form id="addCourse" name="addCourse">
<input type="text" id="courseID" name="courseID" value="courseID" size="40" /><br />
<textarea rows="5" cols="33" id="courseDesc" name="courseDesc">Description</textarea><br />
<input type="button" value="Add Course" onclick="addCourse(this.courseID.value, this.courseDesc.value);"/>
</form>
</div>
Here is the Script function:
<script type ="text/javascript">
function addCourse(id, descr)
{
var fluffy;
fluffy=new XMLHttpRequest();
fluffy.onreadystatechange=function()
{
if (fluffy.readyState==4 && fluffy.status==200)
{
//do something here
}
};
fluffy.open("GET","ajaxServlet?courseID="+id+"&courseDescription="+descr,true);
fluffy.send();
}
</script>
Because this is the button and not the form
so
this.courseID.value
this.courseDesc.value
returns an error.
You should use
this.form.courseID.value
this.form.courseDesc.value
Second problem is you have a name clash. The form and function are named addCourse. It will lead to problems. Rename one of them to be different.
Running Example
When you use this, as in onclick="addCourse(this.courseID.value, this.courseDesc.value);", I think that would refer to the input element, and therefore the values aren't being passed correctly.
Bind your event handlers in javascript, where they should be, and you can avoid the issue entirely.
HTML:
<input type="text" id="courseID" name="courseID" value="courseID" size="40" /><br />
<textarea rows="5" cols="33" id="courseDesc" name="courseDesc">Description</textarea><br />
<input type="button" id="addCourse" value="Add Course"/>
JS:
document.getElementById('addCourse').onclick = function () {
var fluffy = new XMLHttpRequest();
var id = document.getElementById('courseID').value;
var descr = document.getElementById('courseDesc').value;
fluffy.onreadystatechange=function() {
if (fluffy.readyState==4 && fluffy.status==200) {
//do something here
}
};
fluffy.open("GET","ajaxServlet?courseID="+id+"&courseDescription="+descr,true);
fluffy.send();
};
As epascarello pointed out, you need to change the ID of your form as having two elements with the same ID is not allowed and will cause unpredictable javascript behavior.
Try a fluffy.close; after the if ready state expression.

Increase/decrease textfield value with javascript

I'm having trouble in doing a javascript that will do the following:
Increase/decrease number inside textbox when image clicked.
setting a limit for that textbox (not below zero, not above x)
please know i have many text boxes in the same page, so how can this issue be fixed?
You don't need to (and shouldn't) set ids for each and every image and input field. You will need to set name attributes for each input field though (so your server code can tell them apart - but not for JS).
If the "add" section for each row looks like:
<div>
<img src='minus.png' onclick="increment(this.parentNode.getElementsByTagName('input')[0]);" />
<input type='text' name='product_1010101011' />
<img src='plus.png' onclick="decrement(this.parentNode.getElementsByTagName('input')[0]);" />
</div>
use this javascript:
function increment(myInput) {
// use Mike Samuel's code here
myInput.value = (+myInput.value + 1) || 0;
}
function decrement(myInput) {
// use Mike Samuel's code here
myInput.value = (myInput.value - 1) || 0;
}
I think this should get you going:
<form>
<input type="button" id="minus" value="-"
onClick="textb.value = (textb.value-1)">
<input type="text" id="textb" name="name" value="1" />
<input type="button" value="+"
onClick="textb.value = (+textb.value+1)">
</form>
Live example here
To increment
myInput.value = (+myInput.value + 1) || 0;
To decrement
myInput.value = (myInput.value - 1) || 0;
The || 0 will reset any value that doesn't parse as an integer to a default value, 0.

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