Develop Reference

Trying to create a random game but doesn't seem to work

Under my form action, I called the textbox and buttons. It was suppose for the user to key in 2 values one being the highest value and another being the lowest value, it will then generate a random value between the lowest and the highest. The user will than guess the number if its correct it will print out the message correct
<form action="random" method="get" onSubmit="return validate()">
Lowest number:
<input id="digit" type="text" name="lowestnumber" onchange="validate()"><br/>
<br/><span id="numbers"></span>
Highest number:
<input id="digit1" type="text" name="highestnumber" onchange="validate()">
<br/><span id="numbers1"></span>
<br/><input id="rand" type="submit" value="submit" onclick="Random()"><br/>
<input id="guess" type="text" value="Random Number Generator">
<br/>Enter your number<br/>
<input id="textbox" type="text"><br/>
<input id="guessing" type="button" value="Random" onclick="RandomNumber()"><br/>
<br/><span id="correct"></span>
</form>
My script consist of the methods and functions to use, I think the problem lies at the RandomNumber() function, im not sure where did I go wrong, but please assist me
function validate()
{
var values = document.getElementById("digit").value;
if(values<0)
{
document.getElementById("numbers").innerHTML = "This is not a number, number must be greater or equal to zero"
return false
}
else if (!(typeof +values && values >= 0)|| values.trim() == "")
{
document.getElementById("numbers").innerHTML = "Fill in a number";
return false;
}
else if (values>=0)
{
document.getElementById("numbers").innerHTML = "";
}
var values1 = document.getElementById("digit1").value;
if(values1<0)
{
document.getElementById("numbers1").innerHTML = "This is not a number, number must be greater or equal to zero"
return false
}
else if (!(typeof +values1 && values1 >= 0)|| values1.trim() == "")
{
document.getElementById("numbers1").innerHTML = "Fill in a number";
return false;
}
else if (values >= values1)
{
document.getElementById("numbers1").innerHTML = "Highest number is smaller than lowest number";
return false;
}
else if (values1 > values)
{
document.getElementById("numbers1").innerHTML = "";
}
if((document.getElementById("digit").value>0) && (document.getElementById("digit1").value>0))
{
document.getElementById("rand").removeAttribute('disabled');
}
else
{
document.getElementById("rand").setAttribute('disabled', 'disabled');
}
}
This is the function to generate a random number in between the lowest number and the highest number.
function Random()
{
var value1 = document.getElementById("digit").value;
var value2 = document.getElementById("digit1").value;
minvalue= Math.ceil(value1);
maxvalue= Math.floor(value2);
var random = Math.floor(Math.random()*(maxvalue-minvalue)+1+minvalue);
document.getElementById("guess").value=random;
}
And this is the part where I assume it may have cause the entire program to stop working, its after I wrote down this codes and my web page doesn't perform the way I want it to be.
function RandomNumber()
{
var value3 = document.getElementById("digit").value;
var value4 = document.getElementById("digit1").value;
minvalue= Math.ceil(value3);
maxvalue= Math.floor(value4);
var random1 = Math.floor(Math.random()*(maxvalue-minvalue)+1+minvalue);
var maxtries=5;
var counter=0;
var true=document.getElementById("textbox").value;
while(true!=random1)
{
document.getElementById("total").value=total;
counter +=1;
if(counter>maxtries)
{
document.getElementById("correct").innerHTML="No more tries"
}
if(true==random1)
{
document.getElementById("correct").innerHTML="Correct"
}
}
}

When I look at your code I see a couple of red flags.
E.g. true is a reserved keywoard in JS, you can't assign a value to it:
var true=document.getElementById("textbox").value;
This must throw an error in your development console.
Also in your loop while(true!=random1) neither true or random1 are reassigned, so if true in the beginning, the condition will never become false, hence the loop is never left in this case!
In general you should try to narrow your issue down, look at the errors and rather ask for help on smaller snippets where you ask concrete questions. With a statement like my web page doesn't perform the way I want it to be it is hard to provide help.

Querying input text with javascript and checking for a value does not work

I would like to query an input field with Javascript and from a value of over 20 a button should be released. Javascript works too. Unfortunately, if I enter the number with a comma instead of a period, it no longer works.
var checkEmpty_ek = document.querySelector('#ek');
checkEmpty_ek.addEventListener('input', function() {
if (checkEmpty_ek.value >= 20) {
document.getElementById("neuerbuttonspeichern").disabled = false;
} else {
document.getElementById("neuerbuttonspeichern").disabled = true;
}
});
<input type="text" id="ek" name="ek" value="$ek">
<input type="button" id="neuerbuttonspeichern" value="Send" />

Try: let inputValue = Number(checkEmpty_ek.value.replace(",",".")); inside function.
And then check: (inputValue >= 20)
It is not the most elegant solution, but it will resolve if the user types the number with a comma or with letters and special characters.
Bye.

Use type = number
var checkEmpty_ek = document.querySelector('#ek');
checkEmpty_ek.addEventListener('input', function() {
document.getElementById("neuerbuttonspeichern").disabled = checkEmpty_ek.value < 20;
});
$ek<input type="number" id="ek" name="ek" value="0">
<input type="button" id="neuerbuttonspeichern" value="Send" disabled />

if (Number(checkEmpty_ek.value.replace(/,/g, '')) >= 20) {
{
document.getElementById("neuerbuttonspeichern").disabled = false;
} else
{
document.getElementById("neuerbuttonspeichern").disabled = true;
});
If you are just looking to remove any potential commas from the input, this will do it. But like someone else commented, we aren't really familiar with your user interaction expectations. Chances are, you'll be filtering out more than commas.

Just replace the comma with the dot.
Number(checkEmpty_ek.value.replace(",","."))
Number ("20.") === 20
var checkEmpty_ek = document.querySelector('#ek');
checkEmpty_ek.addEventListener('input', function() {
console.log(checkEmpty_ek.value)
if (Number(checkEmpty_ek.value.replace(",",".")) >= 20) {
document.getElementById("neuerbuttonspeichern").disabled = false;
} else {
document.getElementById("neuerbuttonspeichern").disabled = true;
}
});
<input type="text" id="ek" name="ek" value="">
<input type="button" id="neuerbuttonspeichern" value="Send" />

Check the length of the number entered in a textbox

I want to write in text box and check if is integer and less than 16 numbers. I have the following JavaScript codes.
<script type="text/javascript">
function doCheck(field) {
if (isNaN(document.getElementById(field).value)) {
alert('this is not a number');
document.getElementById(field).focus();
document.getElementById(field).select();
return false;
}
else {
return true;
}
}
</script>
<form method="post" action="" onsubmit="return doCheck('number');">
national id=<input type="text" name="nat" id="number">
<input type="submit" name="submit">
</form>

document.getElementById(field).value.length

you can find the length of string inside the text box using this
function doCheck(field) {
var len = document.getElementById("number").val().length;
if(parse.Int(document.getElementById(field).value) && len < 16) {
return true;
}
else {
alert('your alert');
document.getElementById(field).focus();
document.getElementById(field).select();
return false;
}
}

be sure you parse it as an integer.
function doCheck(field) {
var input_value = document.getElementById(field).value;
if(isNaN(input_value) || parseInt(input_value,10) != input_value || input_value.length < 16) {
alert('this is not a number');
document.getElementById(field).focus();
document.getElementById(field).select();
return false;
}
else{
return true;
}
}

isNAN() checks whether a number is an illegal number of any type, not only integer. So you have to use something else there, a regular expressions maybe.
To get the length of the field you can simply use:
document.getElementById(field).value.length

Comparing two input fields

I have this function which i am using to compare two input fields. If the user enters the same number in both the text field. On submit there will be an error. Now i would like to know if there is a way to allow same number but not higher than or lower the value of the previous text box by 1. For example if user enters 5 in previous text box, the user can only input either 4, 5 or 6 in the other input field.Please give me some suggestions.
<script type="text/javascript">
function Validate(objForm) {
var arrNames=new Array("text1", "text2");
var arrValues=new Array();
for (var i=0; i<arrNames.length; i++) {
var curValue = objForm.elements[arrNames[i]].value;
if (arrValues[curValue + 2]) {
alert("can't have duplicate!");
return false;
}
arrValues[curValue] = arrNames[i];
}
return true;
}
</script>
<form onsubmit="return Validate(this);">
<input type="text" name="text1" /><input type="text" name="text2" /><button type="submit">Submit</button>
</form>

A tidy way to do it which is easy to read:
var firstInput = document.getElementById("first").value;
var secondInput = document.getElementById("second").value;
if (firstInput === secondInput) {
// do something here if inputs are same
} else if (firstInput > secondInput) {
// do something if the first input is greater than the second
} else {
// do something if the first input is less than the second
}
This allows you to use the values again after comparison as variables (firstInput), (secondInput).

Here's a suggestion/hint
if (Math.abs(v1 - v2) <= 1) {
alert("can't have duplicate!");
return false;
}
And here's the jsfiddle link, if you want to see the answer

Give them both IDs.
Then use the
if(document.getElementById("first").value == document.getElementById("second").value){
//they are the same, do stuff for the same
}else if(document.getElementById("first").value >= document.getElementById("second").value
//first is more than second
}
and so on.

Javascript - validation, numbers only

I'm trying to get my login form to only validate if only numbers were inputted. I can it to work if the input is only digits, but when i type any characters after a number, it will still validate etc. 12akf will work. 1am will work. How can i get past this?
Part of the Login
<form name="myForm">
<label for="firstname">Age: </label>
<input name="num" type="text" id="username" size="1">
<input type="submit" value="Login" onclick="return validateForm()">
function validateForm()
{
var z = document.forms["myForm"]["num"].value;
if(!z.match(/^\d+/))
{
alert("Please only enter numeric characters only for your Age! (Allowed input:0-9)")
}
}

Match against /^\d+$/. $ means "end of line", so any non-digit characters after the initial run of digits will cause the match to fail.
Edit:
RobG wisely suggests the more succinct /\D/.test(z). This operation tests the inverse of what you want. It returns true if the input has any non-numeric characters.
Simply omit the negating ! and use if(/\D/.test(z)).

here is how to validate the input to only accept numbers this will accept numbers like 123123123.41212313
<input type="text"
onkeypress="if ( isNaN(this.value + String.fromCharCode(event.keyCode) )) return false;"
/>
and this will not accept entering the dot (.), so it will only accept integers
<input type="text"
onkeypress="if ( isNaN( String.fromCharCode(event.keyCode) )) return false;"
/>
this way you will not permit the user to input anything but numbers

This one worked for me :
function validateForm(){
var z = document.forms["myForm"]["num"].value;
if(!/^[0-9]+$/.test(z)){
alert("Please only enter numeric characters only for your Age! (Allowed input:0-9)")
}
}

Late answer,but may be this will help someone
function isNumber(n) {
return !isNaN(parseFloat(n)) && isFinite(n);
}
Use will be like
nn=document.forms["myForm"]["num"].value;
ans=isNumber(nn);
if(ans)
{
//only numbers
}
This ans was found from here with huge vote
Validate numbers in JavaScript - IsNumeric()

function validateNumber(e) {
const pattern = /^[0-9]$/;
return pattern.test(e.key )
}
<input name="username" id="username" onkeypress="return validateNumber(event)">
This approach doesn't lock numlock numbers, arrows, home, end buttons and etc

The simplest solution.
Thanks to my partner that gave me this answer.
You can set an onkeypress event on the input textbox like this:
onkeypress="validate(event)"
and then use regular expressions like this:
function validate(evt){
evt.value = evt.value.replace(/[^0-9]/g,"");
}
It will scan and remove any letter or sign different from number in the field.

No need for the long code for number input restriction just try this code.
It also accepts valid int & float both values.
Javascript Approach
onload =function(){
var ele = document.querySelectorAll('.number-only')[0];
ele.onkeypress = function(e) {
if(isNaN(this.value+""+String.fromCharCode(e.charCode)))
return false;
}
ele.onpaste = function(e){
e.preventDefault();
}
}
<p> Input box that accepts only valid int and float values.</p>
<input class="number-only" type=text />
jQuery Approach
$(function(){
$('.number-only').keypress(function(e) {
if(isNaN(this.value+""+String.fromCharCode(e.charCode))) return false;
})
.on("cut copy paste",function(e){
e.preventDefault();
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<p> Input box that accepts only valid int and float values.</p>
<input class="number-only" type=text />
The above answers are for most common use case - validating input as a number.
But to allow few special cases like
negative numbers & showing the invalid keystrokes to user before
removing it, so below is the code snippet for such special use cases.
$(function(){
$('.number-only').keyup(function(e) {
if(this.value!='-')
while(isNaN(this.value))
this.value = this.value.split('').reverse().join('').replace(/[\D]/i,'')
.split('').reverse().join('');
})
.on("cut copy paste",function(e){
e.preventDefault();
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<p> Input box that accepts only valid int and float values.</p>
<input class="number-only" type=text />

Regular expressions are great, but why not just make sure it's a number before trying to do something with it?
function addemup() {
var n1 = document.getElementById("num1");
var n2 = document.getElementById("num2");
sum = Number(n1.value) + Number(n2.value);
if(Number(sum)) {
alert(sum);
} else {
alert("Numbers only, please!");
};
};

function ValidateNumberOnly()
{
if ((event.keyCode < 48 || event.keyCode > 57))
{
event.returnValue = false;
}
}
this function will allow only numbers in the textfield.

I think we do not accept long structure programming we will add everytime shot code see below answer.
<input type="text" oninput="this.value = this.value.replace(/[^0-9.]/g, ''); this.value = this.value.replace(/(\..*)\./g, '$1');" >

Using the form you already have:
var input = document.querySelector('form[name=myForm] #username');
input.onkeyup = function() {
var patterns = /[^0-9]/g;
var caretPos = this.selectionStart;
this.value = input.value.replace(patterns, '');
this.setSelectionRange(caretPos, caretPos);
}
This will delete all non-digits after the key is released.

var elem = document.getElementsByClassName("number-validation"); //use the CLASS in your input field.
for (i = 0; i < elem.length; i++) {
elem[i].addEventListener('keypress', function(event){
var keys = [48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 0];
var validIndex = keys.indexOf(event.charCode);
if(validIndex == -1){
event.preventDefault();
}
});
}

If you are using React, just do:
<input
value={this.state.input}
placeholder="Enter a number"
onChange={e => this.setState({ input: e.target.value.replace(/[^0-9]/g, '') })}
/>
<div id="root"></div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.4.2/react.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.4.2/react-dom.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/6.21.1/babel.min.js"></script>
<script type="text/babel">
class Demo extends React.Component {
state = {
input: '',
}
onChange = e => {
let input = e.target.value.replace(/[^0-9]/g, '');
this.setState({ input });
}
render() {
return (
<div>
<input
value={this.state.input}
placeholder="Enter a number"
onChange={this.onChange}
/>
<br />
<h1>{this.state.input}</h1>
</div>
);
}
}
ReactDOM.render(<Demo />, document.getElementById('root'));
</script>

// I use this jquery it works perfect, just add class nosonly to any textbox that should be numbers only:
$(document).ready(function () {
$(".nosonly").keydown(function (event) {
// Allow only backspace and delete
if (event.keyCode == 46 || event.keyCode == 8) {
// let it happen, don't do anything
}
else {
// Ensure that it is a number and stop the keypress
if (event.keyCode < 48 || event.keyCode > 57) {
alert("Only Numbers Allowed"),event.preventDefault();
}
}
});
});

Avoid symbols like "." "," "+" "-". I tried it and it works fine.
$('#example').keypress(function (evt) {
if (evt != null && evt.originalEvent != null && /\D/.test(evt.originalEvent.key)) {
evt.preventDefault();
evt.stopImmediatePropagation();
return false;
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input name="example" id="example">