When working with a JavaScript function I want to prevent characters from being entered into a form if they do not meet certain parameters. The original JavaScript code I used was:
function validateLetter() {
var textInput = document.getElementById("letter").value;
var replacedInput = textInput.replace(/[^A-Za-z]/g, "");
if(textInput != replacedInput)
alert("You can only enter letters into this field.");
document.getElementById("letter").value = replacedInput;
}
That function worked while I was using only 1 input point in my form, however when I tried to use that function over multiple inputs it would only affect the first one in the form.
When creating a function that could be reused by multiple input boxes I got the following code:
function validateLetter(dataEntry){
try {
var textInput = dataEntry.value;
var replacedInput = textInput.replace(/[^A-Za-z]/g);
if (textInput != replacedInput)
throw "You can only enter letters into this field.";
}
catch(InputError) {
window.alert(InputError)
return false;
}
return true;
}
The form I am using to input information is:
<form action="validateTheCharacters" enctype="application/x-www-form-urlencoded">
<p>Enter your mother's maiden name:
<input type="text" id="letter" name="letter" onkeypress="validateLetter();" />
</p>
<p>Enter the city you were born in:
<input type="text" id="letter" name="letter" onkeypress="validateLetter();" />
</p>
<p>Enter the street you grew up on:
<input type="text" id="letter" name="letter" onkeypress="validateLetter()">
</p>
</form>
Does anyone know a way to translate the last line of the first function: document.getElementById("letter").value = replacedInput;
To something that can be re-used with the current code.
I tried:
dataEntry.value = replacedInput
But that did not seem to run/change the function at all
The problem is in textInput.replace() - you forgot the second parameter. So instead of textInput.replace(/[^A-Za-z]/g);, you need textInput.replace(/[^A-Za-z]/g, "");.
As noted in the MDN website:
The ID must be unique in a document, and is often used to retrieve the element using getElementById.
In your example above, you are using the same value for the ID attribute on all of the input fields. Also, the name attribute should be unique within forms. The answer provided here explains in greater depth. With that said, in the examples below I have modified your input fields in respect to the above.
First off, the initial function you provided was pretty close. One issue with it is that the replace() method would need a second parameter. This parameter can be a string or a function to be called for each match. In your case I believe you just want an empty string:
function validateLetter() {
var textInput = document.getElementById("letter").value;
var replacedInput = textInput.replace(/[^A-Za-z]/g, "");
if(textInput != replacedInput)
alert("You can only enter letters into this field.");
document.getElementById("letter").value = replacedInput;
}
Secondly, you can reference the current input field that is invoking validateLetter() by passing it along to the function as a parameter using the keyword this.
onkeypress="validateLetter(this);"
On a sidenote: You might achieve a better user experience using onkeyup instead of onkeypress. The example below utilizes this event instead so you can compare and judge for yourself.
Here is everything put together in a working example:
function validateLetter(target) {
var textInput = target.value;
var replacedInput = textInput.replace(/[^A-Za-z]/g, "");
if(textInput != replacedInput)
alert("You can only enter letters into this field.");
target.value = replacedInput;
}
<form action="validateTheCharacters" enctype="application/x-www-form-urlencoded">
<p>Enter your mother's maiden name:
<input type="text" id="maiden" name="maiden" onkeyup="validateLetter(this);" />
</p>
<p>Enter the city you were born in:
<input type="text" id="city" name="city" onkeyup="validateLetter(this);" />
</p>
<p>Enter the street you grew up on:
<input type="text" id="street" name="street" onkeyup="validateLetter(this)">
</p>
</form>
Related
Create an html page with the following form:
<form method="post" name="example" action="">
<p> Enter your name <input type="text"> </p>
<input type="submit" value="Submit Information" />
</form>
<div id="a"></div>
Add a js validation function to the form that ensures that you can only add numbers in the textbox If you enter alphabets, you should generate an error message in the given div. -->
I run the requirement successfully and I'm giving the error message when it entered alphabets. However, it's giving me the same error message when I enter digits as well. Please kindly show how the function or the window.onload should be implemented. Thank you.
My answer is down below;
window.onload = function() {
let form = document.getElementById('form_ref')
form.onsubmit = function() {
let user = form.user.value;
if (parseInt(user) !== user) {
document.querySelector('div').innerHTML = "Error! Please enter digits only!";
return false;
}
return true;
}
}
<form id="form_ref" method="post" name="example" action="">
<label for="username">User</label><input type="text" name="user" id="username" required>
<div id="a"></div>
<br>
<input type="submit" value="Submit Information" id="submit">
</form>
Your equality check parseInt(user) !== user will always return true because form.user.value is a string but parseInt(...) always returns an integer. If you want to check if the entry is an integer there are a couple ways.
You can change the input's type attribute to number to make sure only digits can be entered and then you just have to make sure it's an integer and not a decimal (type="number" still allows decimal numbers so not just digits). user will still be a string, but it's easier to check. I'd recommend using Number.isInteger(...) to do the checking:
if (!Number.isInteger(parseFloat(user))) {
If you really want to use type="text" you can iterate through user and make sure its characters are all digits:
for(let i = 0; i < user.length; i++) {
if("0123456789".indexOf(user[i]) == -1) {
document.querySelector('div').innerHTML = "Error! Please enter digits only!";
return false;
}
}
return true;
One advantage of this method is that you can make more characters available if you want to just by adding them to the string that's searched in the iteration. A disadvantage is that it's slower than the other method (the indexOf method has to iterate through the string for every character of user), but for your use case that seems irrelevant-- this function doesn't need to be called many times per second as it's a simple login type of thing, and it's client-side so you don't need to handle many instances at once. If speed is an issue you could probably make a comparison to the integer equivalencies of the characters:
if(user.charCodeAt(i) < "0".charCodeAt(0) || user.charCodeAt(i) > "9".charCodeAt(0)) {
I have a strange error Or I'm being dumb and when I search for my error I don't get the answer I need.
I am trying to have some javascript run if a certain key "/" is pressed in a text box.
Here is the Code:
function ClockIn(){
var kb_press = event.keyCode;
if(kb_press == 47)
{
alert("you are clocking in");
if(document.ClockIn.status.value === "IN"){
alert("You Cant Clock in wile you are already Clocked in\n Please try again!")
document.ClockIn.tx_Barcode.value, document.ClockIn.status.value, document.ClockIn.name.value = "";
}
}
}
<form method="POST" name="ClockIn">
<lable>Type your BarCode <input type="text" name="tx_Barcode" id="tx_Barcode" class="tx_Barcode" onkeypress="ClockIn()" ></lable><br>
<lable>Is your Name? <input type="text" name="name"></lable><br>
<lable>You are currently Signed <input type="text" name="status"></lable><br>
</form>
My result is: ClockIn is not a function
The problem here is you've named your "ClockIn" form, so due to age-old quirks in how HTML interacts with JavaScript, the ClockIn form overwrites your global ClockIn function.
Maybe rename the form "ClockInForm"? Better yet, though, you might want to use document.getElementById("...") to refer to elements.
So I know how to do the remove/add class/attribute from a submit button, but I need to be able to apply this to a button based off of entry into an input.
The scenario is this, user enters their email address, but if it's at a specific domain, ex: xxxx#troopers.gov I then want to be able to apply/remove the class, and attribute from the submit button, since this is a domain they are not supposed to enter for a registration.
I have done some similar validation in the past, and tried a few different methods in jQuery .val(), indexOf, etc. But still can't seem to get it working.
I tried something like
var badDomain = 'troopers.gov';
and then
if (!$('#input').val() === badDomain) {
doStuff();
}
but it didn't seem to get me anywhere.
I thought I may be able to do this without using a RegEx (I don't have much experience with that)
Would be nice to be able to account for case as well... and I don't mind if the solution is jQuery, or pure JS... for learning purposes, it would be great to see how I could do it both ways...
So this does what you want, by turning anything typed into the field in lower case and then comparing against a given array of bad strings. Any time the input field blurs, it checks and turns the submit on or off.
Take a look in the code to see some bad addresses for sample use.
var badDomains = [
"troppers.com",
"fooBarBaz.org",
"myReallyUselessDomainName.com",
"a.net"
]
$(function(){
$("#email").on("blur", function(){
var addressBad = false;
var thisEmail = $(this).val().toLowerCase();
for (var i=0; i<badDomains.length; i++){
if (thisEmail.includes(badDomains[i])){
addressBad = true;
}
}
if (addressBad) {
console.log("bad address!")
$(".disabledButton").attr('disabled', "disabled");
} else {
console.log("not a bad address!");
$(".disabledButton").removeAttr("disabled");
}
})
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form>
<label for="email">Email:</label>
<input type="text" name="email" id="email" />
<input class="disabledButton" type="submit" disabled />
</form>
simple workaround :
var email = document.getElementById('email');
var checkEmail = document.getElementById('checkEmail');
checkEmail.onclick = function() {
if ((email.value).includes('#troopers.gov')) alert('This email address cannot be used!');
}
<input id="email">
<button id="checkEmail">Check Email</button>
there are multiple ways around though.
You can use a regex for this purpose.
HTML:
<input type="text" id="InputTest" />
<button id="TestBtn" type="button">
Validate
</button>
<p>
Valid
</p>
CSS:
.valid{
background-color:green;
}
.invalid{
background-color: red;
}
JS:
$("#TestBtn").on("click",function() {
var pattern = /\S+#troopers\.com/gi;
var str = $("#InputTest").val();
var arr = str.match(pattern);
alert(arr); // just to see the value
if(arr !== null){
$("p").addClass("invalid");
}
else{
$("p").addClass("valid");
}
});
Here is a JSFiddle. Basically, if what the user typed in the textbox matches the expression.. then the background color turns red, but if it doesn't match, then the background color turns green.
Let me know if this helps.
You can use the following Regex for the Email property of the related Model in order to accept mails having 'abc.com' suffix:
[RegularExpression("^[a-zA-Z0-9_#./#&+-]+(\\.[a-zA-Z0-9_#./#&+-]+)*#abc.com$",
ErrorMessage = "Please enter an email with 'abc.com' suffix")]
I have a form which has input fields that expect numbers only.
I'm using javascript to validate the form when the value of the field changes.
If the value is numeric, do nothing.
If the value is not numeric, set it to zero and put focus in that text field. Essentially, I'm trying to trap the cursor in that field until a numeric value is entered. For some unknown reason, focus is not being placed on that form element. cell.focus() does not work. I've even tried document.getElementById(cel.getAttribute("ID")).focus(); What might I be doing wrong?
<html>
<head>
<script>
function NAN(cell){
if (cell.value != "") {
var re = /^(0|[1-9][0-9]*)$/;
if (re.test(cell.value) == false) {
alert('You must supply a numeric value greater than 0.');
cell.value = "0";
cell.focus();
}
}
}
</script>
</head>
<body>
<input type="text" name="num" value="" onchange="NAN(cell)"/>
</body>
</html>
Your problem is in the onchange attribute:
<input type="text" name="num" value="" onchange="NAN(cell)"/>
The value is executed as JavaScript code directly. You're passing code, not just a generic signature or prototype.
Inside those event handler snippets, there's a special object this defined, referring to the current DOM element (the input tag in this example).
(Just to mention it, there is also a second predefined object event, which most likely caused your confusion.)
As a simple fix for your issue, replace cell with this in the call and it should work:
<input type="text" name="num" value="" onchange="NAN(this)"/>
It's also important to note that you should keep in mind that this verification requires JavaScript to be executed. If it's disabled, the user might still pass any values, so you should check the value server side as well (assuming this isn't just client-only code).
As an alternative to using JavaScript, you could just use HTML5 to force a specific pattern on inputs. In this case this would be trivial to do:
<input type="text" name="num" value="" pattern="(?!0)\d+" title="Quantity">
The user won't be able to submit the form unless the pattern is validated, so there's no need to force the input focus. The pattern always has to match the full value, from beginning to the end. The title attribute is typically used to provide more information in the error popup.
There are two things done:
You have to change cell to this with onchange.
According to this question at least with Firefox setTimeout has to wrap this focus-method so that it works as expected.
And a more user-friendly approach is inserted as well at the second input-field.
Hope this example helps you:
function NAN(cell) {
if (cell.value != '') {
var re = /^(0|[1-9][0-9]*)$/;
cell.value = cell.value[0]=='0'?+cell.value:cell.value;
if (re.test(cell.value) == false) {
alert('You must supply a numeric value greater than 0.');
cell.value = '0';
setTimeout(function () {
cell.select();
cell.focus();
}, 0);
}
}
}
/*
* a more user friendly approach
*/
function NAN2(cell) {
if (cell.value != '') {
var re = /^(0|[1-9][0-9]*)$/;
cell.value = cell.value[0]=='0'?+cell.value:cell.value;
if (re.test(cell.value) == false) {
alert('You must supply a numeric value greater than 0.');
cell.value = '0';
setTimeout(function () {
cell.select();
cell.focus();
markElement(cell);
}, 0);
}
else{
tickElement(cell);
}
}
}
function tickElement(cell){
cell.setAttribute('style','border: 1px solid green');
}
function markElement(cell){
cell.setAttribute('style','border: 1px solid red');
}
<p>
Your approach(onchange):
<input type="text" name="num" value="" onchange="NAN(this)"/>
</p>
<p>
Or you can use a more user friendly approach to notify an user right now when they are tipping something wrong (onkeyup):
<input type="text" name="num" value="" onkeyup="NAN2(this)"/>
</p>
I want to create a form and want to validate user input, if user fill both text box i want to show an alert box, also if user fill one and left empty another one i want to show an alert box to let them know that they are missing one box. How i can do it with JavaScript, please help.
I want two text box, if user fill both text box and click enter i want to show an alert box telling them "Correct", if user fill one and left another empty i want to show an alert box telling them that it is "Incorrect".
How i can do it, help.
<form action="" method="post">
<input type="text" name="text1" placeholder="Text 1">
</br>
<input type="text" name="text2" placeholder="Text 2">
</br>
<input type="submit" value="Enter">
</form>
What kind of validation are you interested in ?
You can do everything with javascript my friend:).
This is pure javascript. To make it simple, I kept the html and js in one file. I also added a name to a form as you see below, in case you would have multiple forms.
<html>
<body>
<form name="LovelyForm" action="" method="post">
<input type="text" name="text1" placeholder="Text 1"> </br>
<input type="text" name="text2" placeholder="Text 2"> </br>
<input type="submit" onclick="validateForm()" value="Enter">
</form>
<script type="text/javascript">
function validateForm() {
var x = document.forms["LovelyForm"]["text1"].value;
var y = document.forms["LovelyForm"]["text2"].value;
if (x == null || x == "" || y == null || y == "") {
alert("Fill me in");
return false;
}else{
alert("Good");
return true;
}
}
</script>
</body>
</html>
Validation with javascript is the most flexible way and works with all browsers, if you learn JQuery you will be able to improve the user experience limit less.
If you don't want to javascript then use the new improved input validation options with Html 5, they will work with most browsers and not break the ones without Html5 support.
Here: Best practice as I see it :)
Only validate the most necessary on client side.
Avoid compulsory input unless they realy are.
Don't refuse space, hyphens, commas, dots and so on if you absolutely don't have to. People like to cut and paste. You can always clean on server side.
Don't limit input length/size if you don't have to. Again people like to cut and paste and many times the input is to long just because it contains blank spaces.
Most important of all. You must always validate on server side, to make sure your data won't get corrupted. Client validation is only to improve the users experience and not a substitute.
Here's a JSFiddle that should work with IE < 9: http://jsfiddle.net/ayr7yov7/1/
form.elements['one'].value may cause issues if the inputs are not of type text.
The code:
<script>
function trim(str) {
if(!str) return '';
return str.replace(/\s{2,}/g, '');
}
function valid(form) {
var v1 = trim(form.elements['one'].value),
v2 = trim(form.elements['two'].value);
if (v1 === '') {
alert('one');
return false;
}
if (v2 === '') {
alert('two');
return false;
}
alert('full!')
return true;
}
</script>
<form action="/echo/json/" onsubmit="return valid(this)">
<input name="one" type="text" />
<input name="two" type="text" />
<input type="submit" />
</form>
First step is to give JavaScript an easy way to reference the element in the DOM. Generally, the easiest way is to give each element you need to reference a unique ID.
<input id="num1" />
<input id="num2" />
Then, JavaScript can access the inputs with the getElementById() method of the document object (the "D" from DOM).
var i1 = document.getElementById("num1");
var i2 = document.getElementById("num1");
Now, i1 and i2 contain a reference to their respective input objects (the "O" from DOM). Every form element object has a value attribute that contains the current value of it's input.
var val1 = i1.value;
var val2 = i2.value;
Now var1 and var2 contain the value of the input. All you have to do is check and see if they both have a value that isn't empty.
if(
// if the first value does not equal an empty string ""..
val1 != ""
// and the second value does not equal an empty string ""..
&& val1 != ""
)
// then alert 'correct'
alert("correct");
// or else, alert 'incorrect'
else alert('incorrect');
Now you can throw it in a function and make it run when the form is submitted by attaching it to an event handler. When you're just starting it's easiest to use an onsubmit attribute, which takes the name of a function and calls that function when the form is submitted.
<form action="#" onsubmit="validate()">
<input id="num1" />
<input id="num2" />
<input type="submit" />
</form>
<script>
function validate(){
var i1 = document.getElementById("num1");
var i2 = document.getElementById("num1");
var val1 = i1.value;
var val2 = i2.value;
if(val1 != "" && val2 != "") alert("correct");
else alert("incorrect");
}
</script>