When working on a page whenever I call on my second function, validateNumber(), I get a "typeError: String is not a function" message can anyone explain to me why this message is occuring? My code is as follows:
< script type = "text/javascript" >
/* <![CDATA[ */
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.";
dataEntry.value = replacedInput;
} catch (textInputError) {
window.alert(textInputError)
return false;
}
return true;
}
function validateNumber(dataEntry) {
try {
var textInput = dataEntry.value;
var replacedInput = textInput(/[^0-9]/g);
if (textInput != replacedInput)
throw "You can only enter numbers into this field.";
} catch (numberInputError) {
window.alert(numberInputError)
return false;
}
return true;
}
function validateInput(dataEntry) {
if (navigator.appName == "Microsoft INternet Explorer")
var enteredKey = dataEntry.keyCode;
else if (navigator.appName == "Netscape")
var eneteredKey = dataEntry.charCode;
}
/* ]] */
< /script>
<form action="validateTheCharacters" enctype="application/x-www-form-urlencoded" name="dataEntry">
<p>Enter your mother's maiden name:
<input type="text" id="letter1" name="letter1" onkeypress="validateLetter(this)">
</p>
<p>Enter the city you were born in:
<input type="text" id="letter2" name="letter2" onkeypress="validateLetter(this)">
</p>
<p>Enter the street you grew up on:
<input type="text" id="letter3" name="letter3" onkeypress="validateLetter(this)">
</p>
<p>Enter your phone number:
<input type="text" id="number1" name="number1" onkeypress="validateNumber(this)">
</p>
<p>Enter the year you were born:
<input type="text" id="number2" name="number2" onkeypress="validateNumber(this)">
</p>
<p>Enter the number of siblings you have:
<input type="text" id="number3" name="number3" onkeypress="validateNumber(this)">
</p>
<p>
<button type="reset" value="Reset Form">Reset Form</button>
</p>
</form>
I am almost certain this is the problem:
var textInput = dataEntry.value;
var replacedInput = textInput(/[^0-9]/g);
if textInput is a string you cannot pass parameters to it as if it were a function, instead:
var replacedInput = textInput.replace(/[^0-9]/g, ""); // dependening in what you are trying to achieve of course
var replacedInput = textInput(/[^0-9]/g);
That's not how you do search and replace in Javascript.
It's not quite clear what you intended here, but if you wanted to remove non-digits from the string, you'd do that using String.replace():
var replacedInput = textInput.replace(/[^0-9]/g, "");
That being said, an easier way of accomplishing this check would be to skip the replacement entirely and just use String.match() instead:
var textInput = dataEntry.value;
if (textInput.match(/[^0-9]/))
throw "You can only enter letters into this field.";
dataEntry.value = textInput;
You might consider isolating functionality so that functions like validateLetter simply validate that the string they are passed contains only letters, then have the caller function work out what to do if the return value is true or not.
In that case, you end up with very much simpler functions:
function validateLetters(s) {
return /^[a-z]+$/i.test(s);
}
function validateNumbers(s) {
return /^\d+$/.test(s);
}
To validate an input, you can add a class to say what type of validation it should have, e.g.
<input name="letter3" class="letter" onkeypress="validateLetter(this)">
Then the validateInput function can determine which validation function to call based on the class:
function validateInput(element) {
var value = element.value;
// If has class letter, validate is only letters
if (/(\s|^)letter(\s|$)/i.test(element.className)) {
// validate only if there is a value other than empty string
if (!validateLetters(value) && value != '') {
alert('Please enter only letters');
}
}
// If has class number, validate is only numbers
if (/(\s|^)number(\s|$)/i.test(element.className)) {
// validate only if there is a value other than empty string
if (!validateNumbers(element.value) && value != '') {
alert('Please enter only numbers');
}
}
}
Note that keypress is not a good event to use for validation as data can be entered without pressing any keys (e.g. paste from the context menu or drag and drop). Also, the listener doesn't see the value resulting from the keypress, it sees the previous value.
You really only need to perform validation when the form is submitted. Until then, why do you care what the values are? Allow the user to make mistakes and fix them themselves without being pestered by alerts (onscreen hints are really useful). Spend some time using your forms to enhance their usability (I realise this is probably not a production form, but names can have characters other than the letters a to z, e.g. von Braun and O'Reilly).
Lastly, form controls rarely need an ID, the name is usually sufficient to identify them if required (and they must have a name to be successful, so most have a name already). A bit of play HTML from the OP:
<form>
<p>Enter your mother's maiden name:
<input name="letter1" class="letter" onkeypress="validateInput(this)">
</p>
<p>Enter the number of siblings you have:
<input name="number3" class="number" onkeypress="validateInput(this)">
</p>
<p>
<input type="reset">
</p>
</form>
Related
Im trying to display an error message in RED beside the input field to let the user know, however I dont know why my error message is not working. The requirement for the input is starting with a capital letter, followed by non special characters (any alphabets) please help me see what is wrong with my code
I am still new to HTML and I know many people said about regex but im not sure i have not learn that
<html>
<script>
function validateForm() {
var fname = document.getElementById("fname").value;
if (/^[A-Z]\D{2,30}$/.test(fname) == false)
{
document.getElementById("errorName").innerHTML = "Your email must be filled";
return false;
{
return name;
}
</script>
<style>
#errorName
{
color:red;
}
</style>
<form action="handleServer.php" method="get" onSubmit="return validateForm()">
<body>
<!-- starting with first name-->
First name: </br>
<input id="fname" type="text" name="fname" size="30">
<span id="errorName"></br>
<input type="submit" value="Submit">
</body>
</form>
</html>
I see your if statements are not closed properly and also the input box.
Please find codepan
function validateForm() {
console.log(1);
var fname = document.getElementById("fname").value;
if (/^[A-Z]\D{2,30}$/.test(fname) == false)
{
document.getElementById("errorName").innerHTML = "Your email must be filled";
return false;
{
return name;
}
}
}
When i tend to use regex i store it in its own value like this:
const patternName = /[0-9]|[-!$%^&*()_+|~=`{}\[\]:";'<>?,.\/|#]/;
let resultName = patternName.test(name.value);
The code above checks if the name contains anything from the regex above and if it does resultName will return true.
Next we can do the following:
If name is empty you get an error and it contains anything from the regex above we. In this case we show the error
If resultName is true we know that name contains something from the regex, so that it's not a valid name.
If not we show success message
if (name.value === "" || resultName) {
showErrorName();
} else {
showSuccessName();
}`
I have a problem
I make a check when you enter upper or lower case letters in the text input to warn that letters cannot be entered but only numbers.
how to make i only enter numbers in the input?
<input type="text" id="texter">
<button onclick="checker()">
START
</button>
checker = () =>{
var texter = document.getElementById('texter').value;
if(texter.search(/[a-z]/)){
alert("letters");
return false;
}
else if(texter.search(/[A-Z]/)){
alert("letters big");
return false;
}
else{
return true;
}
}
For the best user experience, using type="number" on your input is the best bet.
<input type="number" />
If you need it to be a "text" type, one thing you can do is strip any non-numeric character from the string and set the value of the textbox to this string:
const textbox = document.querySelector('#texter');
textbox.onkeyup = event => {
const stripped = event.target.value.replace(/\D/g,'');
textbox.value = stripped;
}
<input id="texter" />
sorry but why don't just use number type of the input
<input type='number'id='texter' />
here you don't need to check for number this input just accept numbers
I have a problem, that I'm struggling with since 2 days.
I have a webpage that asks for the phone number, and I'm trying to make a "validator" for the phone number into the input tab, but it seems that I cannot figure out how to check the minlength for the input tab, neither how to accept only numerical characters. Here's the code:
$("#start").click(function(){ // click func
if ($.trim($('#phonenr').val()) == ''){
$("#error").show();
I tried adding:
if ($.trim($('#phonenr').val()) == '') && ($.trim($('#phonenr').val().length) < 15)
But it just won't work.
Any help would be appreciated. Also please tell me how can I make it allow only numbers?
Thank you!
Final code, with help of #Saumya Rastogi.
$("#start").click(function(){
var reg = /^\d+$/;
var input_str = $('#phonenr').val();
chopped_str = input_str.substring(0, input_str.length - 1);
if(!reg.test(input_str)) {
$("#error").show();
return;
}
if(($.trim(input_str) == '') || ($.trim(input_str).length < 15)) {
$("#error").show();
} else {
You can make your validation work.
You can use test (Regex Match Test) for accepting only digits in the input text. Just use javascript's substring to chop off the entered non-digit character like this:
$(function() {
$('#btn').on('click',function(e) {
var reg = /^\d+$/; // <------ regex for validatin the input should only be digits
var input_str = $('#phonenr').val();
chopped_str = input_str.substring(0, input_str.length - 1);
if(!reg.test(input_str)) {
$('label.error').show();
return;
}
if(($.trim(input_str) == '') || ($.trim(input_str).length < 15)) {
$('label.error').show();
} else {
$('label.error').hide();
}
});
})
label.error {
display: none;
color: red;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input id="phonenr" type="text" value=""><br>
<label class='error'>Invalid Number</label>
<br><br>
<button id="btn">Click to Validate</button>
Hope this helps!
If you are using HTML5, then you can make use of the new number input type available
<input type="number" name="phone" min="10" max="10">
You can also use the pattern attribute to restrict the input to a specific Regular expression.
If you are looking for the simplest way to check input against a pattern and display a message based on validity, then using regular expressions is what you want:
// Wait until the DOM has been fully parsed
window.addEventListener("DOMContentLoaded", function(){
// Get DOM references:
var theForm = document.querySelector("#frmTest");
var thePhone = document.querySelector("#txtPhone");
var btnSubmit = document.querySelector("#btnSubmit");
// Hook into desired events. Here, we'll validate as text is inputted
// into the text field, when the submit button is clicked and when the
// form is submitted
theForm.addEventListener("submit", validate);
btnSubmit.addEventListener("click", validate);
thePhone.addEventListener("input", validate);
// The simple validation function
function validate(evt){
var errorMessage = "Not a valid phone number!";
// Just check the input against a regular expression
// This one expects 10 digits in a row.
// If the pattern is matched the form is allowed to submit,
// if not, the error message appears and the form doesn't submit.
!thePhone.value.match(/\d{3}\d{3}\d{4}/) ?
thePhone.nextElementSibling.textContent = errorMessage : thePhone.nextElementSibling.textContent = "";
evt.preventDefault();
}
});
span {
background: #ff0;
}
<form id="frmTest" action="#" method="post">
<input id="txtPhone" name="txtPhone"><span></span>
<br>
<input type="submit" id="btnSubmit">
</form>
Or, you can take more control of the process and use the pattern HTML5 attribute with a regular expression to validate the entry. Length and digits are checked simultaneously.
Then you can implement your own custom error message via the HTML5 Validation API with the setCustomValidity() method.
<form id="frmTest" action="#" method="post">
<input type="tel" id="txtPhone" name="txtPhone" maxlength="20"
placeholder="555-555-5555" title="555-555-5555"
pattern="\d{3}-\d{3}-\d{4}" required>
<input type="submit" id="btnSubmit">
</form>
Stack Overflow's code snippet environment doesn't play well with forms, but a working Fiddle can be seen here.
Is there a quick javascript library or code that would only allow a user to start a form input with a preset selection of words?
For example it would allow a user to start a the word "Are" or "What" but not "Why".
You can use the following Regex. (This is really primitive and should be improved according to your case.)
^(Why|Are).*$
HTML5 input pattern example:
<form>
<input type="text" pattern="^(Why|Are).*$">
<input type="submit">
</form>
Test here.
You can add change or input event listener to it and validate the content. To avoid false negatives with initial few letters you can start checking after the input string contains a space. You don't need a library to do that. Plain old JS will do the job.
var input = document.getElementById("myinput");
input.addEventListener('input', validate);
function validate(e) {
var validStart = ['why', 'when'];
var tmpVal;
if (this.value.indexOf(' ') !== -1) {
tmpVal = this.value.toLowerCase().trim();
if (validStart.indexOf(tmpVal) === -1) {
input.classList.add('notvalid');
} else {
input.classList.remove('notvalid');
}
} else {
input.classList.remove('notvalid');
}
}
JSFiddle: http://jsfiddle.net/ofx2yhzm/1/
Very similar to Strah's answer, but here it is anyway:
function checkValue(el) {
// Trim only leading whitespace so responds when first space entered
// and break into words
var words = el.value.replace(/^\s+/,'').split(/\s+/);
// List of allowed words
var allowed = ['are','what'];
// Element to write message based on source element
var msg = document.getElementById(el.id + 'Msg');
// Clear error message by default
msg.innerHTML = '';
// Only do something if at least one word has been entered
// Could also check if first word has more letters than
// longest allowed word
if (words.length > 1) {
// Check if first word is allowed
if ( allowed.indexOf(words[0].toLowerCase()) == -1) {
msg.innerHTML = 'Input must start with one of ' + allowed.join(', ');
}
}
}
Some markup:
<input id="foo" oninput="checkValue(this);">
<span id="fooMsg"></span>
This allows the user to at least enter a word before being given an error. They should also be given some onscreen hints to let them know which words to use, rather than having to get it wrong first (which is bound to happen a lot).
Html:
<form name="myform" method="post" action="#" onsubmit="return validate()">
<input type="text" name="val" />
<input type="submit" value="Submit" />
</form>
Javascript:
window.validate = function(){
data = document.forms['myform']['val'].value;
var starts = ['hi','he'];
for (var i = 0; i <= starts.length; i++)
if (data.indexOf(starts[i]) === 0) return true;
return false;
}
And of course you could also use Regex tho I guess that's a little more inefficient.
Something like this?: http://jsfiddle.net/4jasrbob/
So, I have a number textbox and I want to validate it using JavaScript. If the user has not input any number, it will prompt him/her to enter one. My codes below:
<input type="number" autofocus id="lol"/>
<input type="button" onClick="validate()" value="Input"/>
<script>
function validate() {
var numfield = document.getElementById("lol").value;
if ( numfield == "") {
document.write("Missing number!");
}
</script>
What is wrong?
You have missed a } at the end of the script. With that fixed, it works normally.
Try to use length property.
if ( numfield.length > 0) {
...
}