How would I implement NaN and have Inavlid input display in a element
To do this I have to use isNaN to verify that numerical values are input.
I just want it to display "Invalid input" whenever a non numeric value is put in either of the two first text boxes.
http://jsfiddle.net/hq3m1uns/1/ this is my fiddle link
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Question2</title>
<style>
</style>
<script type="text/javascript">
window.onload = function(){
};
function add_number(){
var first_number = document.querySelector("#tb1").value;
var second_number = document.querySelector("#tb2").value;
var First = parseInt(first_number);
var Second = parseInt(second_number);
var result = First + Second;
document.getElementById('tb3').setAttribute("value",result);
}
</script>
</head>
<body>
<div>
<h1>Add two number using text box as input using javascript</h1>
</div>
Enter First Number : <br>
<input type="text" id="tb1" name="TextBox1">
<br> Enter Second Number : <br>
<input type="text" id="tb2" name="TextBox2">
<br> Result : <br>
<input style="width: 50%" type="text" id="tb3" name="TextBox3" >
<br>
<input onclick="add_number()" type="button" id="b1" value="GO" />
</body>
</html>
Just add a paragraph tag in your HTML file with id "msg" and do the following changes in your javascript code.
function add_number() {
var first_number = document.querySelector("#tb1").value;
var second_number = document.querySelector("#tb2").value;
if (isNaN(first_number) || isNaN(second_number)) {
document.getElementById('msg').innerHTML = "Invalid Input";
} else {
document.getElementById('msg').innerHTML = "";
var First = parseInt(first_number);
var Second = parseInt(second_number);
var result = First + Second;
document.getElementById('tb3').setAttribute("value", result);
}
}
<p id="msg"></p>
One way is to use a keyup event listener on the input field to validate the numeric value and update the textContent of the paragraph element based on its validity.
Another solution is to use a input type="number" for the input and use HTML5's checkValidity/reportValidity on it, but I'll leave that for you to research and learn about on your own.
function validate(inputId, helpId) {
var value = document.getElementById(inputId).value;
var help = document.getElementById(helpId);
if (isNaN(value))
help.textContent = "invalid input"
else
help.textContent = ""
}
Enter First Number : <br>
<input type="text" id="tb1" name="TextBox1" onkeyup="validate('tb1', 'help1')">
<p id="help1"></p>
Related
i'm really absolute beginner, started watching some programming videos.
I have installed VSC, but it's not showing any error when run.
Any program that is better than VSC?
I want to convert Input: Cipto to Output: 01100011 01101001 01110000 01110100 01101111
How do i do it? Please i need some easy code to understand.
function convert() {
var input = document.getElementById("name");
var ouput = document.getElementById("number").value;
}
output.value = "01100011 01101001 01110000 01110100 01101111";
<html>
<head>
<body>
<script src = "1.js"></script>
Type in Cipto:
<br>
<input type = "text" id="name";
<br>
<button onClick="convert();">Convert!</button>
<br>
<br>
Output:
<br>
<input type = "number" value="number";
</form>
</body>
</head>
</html>
firstly you had a typo and wrote ouput instead of oputput. second, you tried to access a variable that was declared in a function from outside of his scope and it's not possible. lastly in HTML input, you should close the tag like a normal tag.
function convert() {
var input = document.getElementById("name");
var output = document.getElementById("number");
output.value = "01100011 01101001 01110000 01110100 01101111";
}
<html>
<head>
<body>
<script src = "1.js"></script>
Type in Cipto:
<br>
<input type="text" id="name">
<br>
<button onClick="convert();">Convert!</button>
<br>
<br>
Output:
<br>
<input type="text" id="number" value="number">
</form>
</body>
</head>
</html>
this code will work but it will always enter the same output to the input field.
if you would like to convert every input to its binary form you should write the convert function differently like so:
function convert() {
var input = document.getElementById("name").value;
var output = document.getElementById("number");
output.value = "";
for (var letter of input) {
output.value += letter.charCodeAt(0).toString(2) + " ";
}
}
<html>
<head>
<body>
<script src = "1.js"></script>
Type in Cipto:
<br>
<input type="text" id="name">
<br>
<button onClick="convert();">Convert!</button>
<br>
<br>
Output:
<br>
<input type="text" id="number">
</form>
</body>
</head>
</html>
I am pretty new here so Don't be mad at me if I get the answer wrong, but you have mistakes both in the html code and the js code.
The html I've modified:
<head>
<body>
<script src = "1.js"></script>
Type in Cipto:
<br>
<input type = "name" id="name">
<br>
<button onClick="convert();">Convert!</button>
<br>
<br>
Output:
<br>
<input id="number">
</form>
</body>
</head>
</html>
and the JavaScript:
function convert() {
var input = document.getElementById("name").value;
var output = document.getElementById("number");
output.value = "";
for(var i = 0; i < input.length; i++) {
document.getElementById("number").value += input[i].charCodeAt(0).toString(2) + " ";
}
}
First on html on both input forms, I've removed everything and just added an id
And in the js function I've went through every character of the input string and converted the ascii value of that character into binary. And that's it!
Hope I helped.
I am trying to add the first two textboxes and then multiply the last one to that value and put that into a textbox but I am getting nowhere please help.
Unclear.
You can give the three textboxes an id and create a variable.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
</head>
<body>
<input id="firsttextbox"></input>
<input id="secondtextbox"></input>
<input id="thridtextbox"></input>
<button onclick="calculate()">Calculate</button>
</body>
</html>
var firstTextbox = document.getElementById('firsttextbox');
var secondTextbox = document.getElementById('secondtextbox');
var thirdTextbox = document.getElementById('thirdtextbox');
Add the firstTextbox value and secondTextbox value and then multiply by third text box
function calculate() {
var sum = firstTextbox.value + secondTextbox.value;
var final = sum * thirdTextbox.value;
}
you need to check each time there's a change in the document. you want to make sure that the user has entered a valid number in the first three text areas
document.addEventListener("change", myScript);
function myScript(){
var texts = document.getElementsByTagName('textarea');
var cnt = 0;
for(let i = 0;i<3;i++){
if(!isNaN(texts[i].value) && texts[i].value!='')cnt++;
console.log(cnt);
}
if(cnt == 3){
texts[3].value = (parseFloat(texts[0].value)+parseFloat(texts[1].value))*parseFloat(texts[2].value);
}
}
<textarea id='a1'></textarea>
<textarea id='a2'></textarea>
<textarea id='a3'></textarea>
<textarea id='a4'></textarea>
<center>
<input type="text" id="t1" name="fname"><br>
<input type="text" id="t2" name="lname"><br>
<input type="text" id="t3" name="lname"><br>
<input type="button" onclick="script:
var out=t1.value+t2.value*t3.value;
alert(out);
"value="Test It Out!!">
</center>
I know that this might be simple, but I was trying to create some sort of system in HTML using Javascript, that when you input a number in the input tag it multiplies it with another number, them outputs the number in another input tag. But for some strange reason, I can't really find out how to do it
<!DOCTYPE html>
<html>
<head>
<script>
var test = document.getElementById('input');
function myFunction() {
document.getElementById('output').value = test + 20;
}
</script>
</head>
<body>
Input: <input id="input">
<button onclick="myFunction()">Submit</button>
<br><br>
<input id="output" type="text">
</body>
</html>
Btw, I don't know how to use JQuery or those types of things, so could you write it in simple HTML?
You should set the value property of an input rather than innerHTML:
Also use parseInt so that you can sum the numbers as input.value will be a string.
function myFunction() {
document.getElementById('output').value = parseInt(test.value, 10) + 20;
}
Here is a working demo: https://jsfiddle.net/usmanmunir/1uv9cqys/8/
function myFunction() {
var test = document.getElementById('input').value;
document.getElementById('output').value = parseInt(test) * 20;
}
Input: <input id="input" type="number">
<button onclick="myFunction()">Submit</button>
<br><br>
Final : <input id="output" type="text">
< Why Input Length Is Undifined
Js
function calc() {
var inp = document.getElementById("inp");
var result = document.getElementById("result");
var inpval = inp.value
result.innerHTML = inpval;
alert(inp.length);
}
Html
<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>
<input id="inp" class="inp" Type="number"/>
<center>
<div id="calc" class="calc" onclick="calc()">Calculate</div>
<br />
<br />
<p id="result"></p>
</center>
</body>
</html>
Please help me with this code I don't know why I am getting this error whenever I click on function it always shows undifined
getElementbyId returns Element and the Element has no length property. This is the reason why that output is undefined. So if you want to get the length of the value of the input element, you have to access input element with value property like inp.value or inpval.
After then, you can get the length of that like inp.value.length or inpval.length.
<!DOCTYPE html><html lang="en">
<head>
<meta charset="UTF-8">
<title>Form</title>
<script>
function billingFunction()
{
var shippingName = document.getElementById("shippingName");
if(document.getElementById("same").checked )
{
document.getElementById("billingName").value= shippingName.value;
}
else
{
document.getElementById("billingName").removeAttribute("required");
}
}
</script>
</head>
<body>
<form>
<fieldset>
<legend>Shipping Information</legend>
<label for ="shippingName">Name:</label>
<input type = "text" name = "Name" id = "shippingName" required><br/>
</fieldset>
<input type="checkbox" id="same" name="same" onchange= "billingFunction()"/>
<label for = "same">Is the Billing Information the Same?</label>
<fieldset>
<legend>Billing Information</legend>
<label for ="billingName">Name:</label>
<input type = "text" name = "Name" id = "billingName" required><br/>
</fieldset>
<input type = "submit" value = "Verify"/>
</form>
</body>
</html>
Whenever the checkbox is checked, the code should automatically copy the values from first field into the second field. If the checkbox is unchecked, the second one should go blank. as per my code the first requirement is ok, but I couldn't make it blank when it is unchecked. Can anyone help plz.
Add document.getElementById("billingName").value = null; to the else clause.
Fiddle
Just set the value to an empty string in the else clause
function billingFunction() {
var shippingName = document.getElementById("shippingName");
var billingName = document.getElementById("billingName");
if(document.getElementById("same").checked ) {
billingName.value = shippingName.value;
} else {
billingName.removeAttribute("required");
billingName.value = "";
}
}
You only need to modify the else block
else{
document.getElementById("billingName").value="";
}
JSFIDDLE
EDIT
You have put the billing function inside header. You must be comming across reference error.
You can put this billing function inside window.onload or pu this script near closing body tag
window.onload= function(){
billingFunction;
}
function billingFunction(){ //Rest of code}
JSFIDDLE with window.onload