Enable submit when all form items are valid - javascript

I need some help with something... say I have the following form...
<form name="" id="" method="" action="">
<input type="text" id="text1" name="text1" />
<br />
<br />
<input type="text" id="text2" name="text2" />
<br />
<br />
<input type="text" id="text3" name="text3" />
<br />
<br />
<input type="text" id="text4" name="text4" />
<br />
<br />
<input type="submit" value="let's go" disabled="disabled" />
</form>
Now I want to have a simple script to enable the submit when the values of the text boxes are not an empty string or null...
So I have something like this.. which I will bind to the window.onload
function enableButton(){
var formitemsArray = ['text1','text2','text3','text4'],
i;
// Loop through all items
for(i=0;i<formitemsArray.length;i++){
// validate the length on the keypress...
formitemsArray.onkeypress = function(){
// loop through all the items again
for(j=0;j<formitemsArray.length;j++){
if(formitemsArray[j] == "" || formitemsArray[j] == null ){
// return false or something???
}else{
document.getElementById("submitButton").disabled = false;
}
}
}
}
}
Now I think I'm on the right lines to a solution but I'm getting lost when trying to make sure that all the items are greater than a zero length string as I'm returning false too soon. Can someone set me straight please?

Welcome to event bubbling!
This does the following: listen to an event (onkeypress) on the whole element and all its children! Which means you can do the following:
document.getElementById('form-id').onkeypress = function(e) {
var text1 = document.getElementById('text1'),
text2 = document.getElementById('text2'),
text3 = document.getElementById('text3'),
text4 = document.getElementById('text4')
if (text1.value.length > 0 &&
text2.value.length > 0 &&
text3.value.length > 0 &&
text4.value.length > 0) {
document.getElementById('submit-button').disabled = false
}
// As an aside, for later: if you want to get the element
// that triggered the event, you have to do the following
// to be cross-browser:
var evt = e || window.event, // IE doesn't get the event passed by argument
target = e.target || e.srcElement // 'target' is official, old versions of FF used 'srcElement'
// With the 'target' variable, you can now play.
}
There is another more generic solution, but it might not fit your needs (note that it requires a forEach shim:
// Declare a counter variable
var count = 0
document.getElementById('form-id').onkeypress = function(e) {
// Get all the inputs!
var inputs = this.getElementsByTagName('input')
// Now loop through all those inputs
// Since a NodeList doesn't have the forEach method, let's borrow it from an array!
[].forEach.call(inputs, loopThroughInputs)
}
function loopThroughInputs(input) {
// First check the type of the input
if (input.type === 'text') {
// If the value is correct, increase the counter
if (input.value.length > 0) {
count++
}
// If the 4 inputs have increased the counter, it's alright!
if (count === 4) {
document.getElementById('submit-button').disabled = false
}
}
}
And now this code was proposed by #Esailija, and it is way better and cleaner. However, it also requires ES5-Shim (for the every method):
document.getElementById('form-id').onkeypress = function(e) {
var inputs = [].slice.call( this.querySelectorAll( '[type=text]') );
document.getElementById('submit-button').disabled = !inputs.every(function(input){
return !!input.value;
});
}
(This guy is brillant, just don't tell him)

There are a few ways you can do this... One would be to keep the button enabled but use javascript to check the validity of the form data upon submission. The benefit to this is that the validation code is only run once, when the user clicks submit and is expecting his data to be validated (at least I do) .
function validateForm() {
var formElement = document.forms[0]; // you didn't give me a name
for(var i = 0, l = formElement.elements.length; i < l; i++ ) {
if( formElement.elements[i].value.length === 0 ) {
return false;
}
return true;
}
}
The other way is live validation, which would validate each input onBlur (focus lost). This method has the benefit of showing the user in real time what values are bad, however this can be very resource heavy depending on the number of form elements and the way you introduce the check.
Personally I would go with my first suggestion; however with that said if you choose to validate each element, I would do so like this:
var formElement = document.forms[0]; // you didn't give me a name
for(var i = 0, l = formElement.elements.length; i < l; i++ ) {
formElement.elements[i].addEventListener('blur', function() {
if( this.value.length === 0 ) {
alert('this input is invalid');
}
}, false);
}
The latter method also requires you hold onto a 'state' variable to determine whether or not the form is valid upon submission, or check all the values again.
Hope this sheds some light, and I hope my code examples help some.

If possible use jquery validation plugin instead of re-inventing the code, http://docs.jquery.com/Plugins/Validation its so easy to use.

In this jsfiddle you'll find a way to monitor the progress of form contents. If all the field conditions are fulfilled, a submit button is shown. Maybe it's useful for you. Bare in mind that client side checking of a form may be tampered with, so you always need a server side check too, if your data need to adhere to certain requirements. In other words: client side form checks are merely usability enhancements.

Related

The radio inputs from my html are not interacting well with my if statements in javascript [duplicate]

I’m having some strange problem with my JS program. I had this working properly but for some reason it’s no longer working. I just want to find the value of the radio button (which one is selected) and return it to a variable. For some reason it keeps returning undefined.
Here is my code:
function findSelection(field) {
var test = 'document.theForm.' + field;
var sizes = test;
alert(sizes);
for (i=0; i < sizes.length; i++) {
if (sizes[i].checked==true) {
alert(sizes[i].value + ' you got a value');
return sizes[i].value;
}
}
}
submitForm:
function submitForm() {
var genderS = findSelection("genderS");
alert(genderS);
}
HTML:
<form action="#n" name="theForm">
<label for="gender">Gender: </label>
<input type="radio" name="genderS" value="1" checked> Male
<input type="radio" name="genderS" value="0" > Female<br><br>
Search
</form>
This works with any explorer.
document.querySelector('input[name="genderS"]:checked').value;
This is a simple way to get the value of any input type.
You also do not need to include jQuery path.
You can do something like this:
var radios = document.getElementsByName('genderS');
for (var i = 0, length = radios.length; i < length; i++) {
if (radios[i].checked) {
// do whatever you want with the checked radio
alert(radios[i].value);
// only one radio can be logically checked, don't check the rest
break;
}
}
<label for="gender">Gender: </label>
<input type="radio" name="genderS" value="1" checked="checked">Male</input>
<input type="radio" name="genderS" value="0">Female</input>
jsfiddle
Edit: Thanks HATCHA and jpsetung for your edit suggestions.
document.forms.your-form-name.elements.radio-button-name.value
Since jQuery 1.8, the correct syntax for the query is
$('input[name="genderS"]:checked').val();
Not $('input[#name="genderS"]:checked').val(); anymore, which was working in jQuery 1.7 (with the #).
ECMAScript 6 version
let genderS = Array.from(document.getElementsByName("genderS")).find(r => r.checked).value;
Here's a nice way to get the checked radio button's value with plain JavaScript:
const form = document.forms.demo;
const checked = form.querySelector('input[name=characters]:checked');
// log out the value from the :checked radio
console.log(checked.value);
Source: https://ultimatecourses.com/blog/get-value-checked-radio-buttons
Using this HTML:
<form name="demo">
<label>
Mario
<input type="radio" value="mario" name="characters" checked>
</label>
<label>
Luigi
<input type="radio" value="luigi" name="characters">
</label>
<label>
Toad
<input type="radio" value="toad" name="characters">
</label>
</form>
You could also use Array Find the checked property to find the checked item:
Array.from(form.elements.characters).find(radio => radio.checked);
In case someone was looking for an answer and landed here like me, from Chrome 34 and Firefox 33 you can do the following:
var form = document.theForm;
var radios = form.elements['genderS'];
alert(radios.value);
or simpler:
alert(document.theForm.genderS.value);
refrence: https://developer.mozilla.org/en-US/docs/Web/API/RadioNodeList/value
Edit:
As said by Chips_100 you should use :
var sizes = document.theForm[field];
directly without using the test variable.
Old answer:
Shouldn't you eval like this ?
var sizes = eval(test);
I don't know how that works, but to me you're only copying a string.
Try this
function findSelection(field) {
var test = document.getElementsByName(field);
var sizes = test.length;
alert(sizes);
for (i=0; i < sizes; i++) {
if (test[i].checked==true) {
alert(test[i].value + ' you got a value');
return test[i].value;
}
}
}
function submitForm() {
var genderS = findSelection("genderS");
alert(genderS);
return false;
}
A fiddle here.
This is pure JavaScript, based on the answer by #Fontas but with safety code to return an empty string (and avoid a TypeError) if there isn't a selected radio button:
var genderSRadio = document.querySelector("input[name=genderS]:checked");
var genderSValue = genderSRadio ? genderSRadio.value : "";
The code breaks down like this:
Line 1: get a reference to the control that (a) is an <input> type, (b) has a name attribute of genderS, and (c) is checked.
Line 2: If there is such a control, return its value. If there isn't, return an empty string. The genderSRadio variable is truthy if Line 1 finds the control and null/falsey if it doesn't.
For JQuery, use #jbabey's answer, and note that if there isn't a selected radio button it will return undefined.
First, shoutout to ashraf aaref, who's answer I would like to expand a little.
As MDN Web Docs suggest, using RadioNodeList is the preferred way to go:
// Get the form
const form = document.forms[0];
// Get the form's radio buttons
const radios = form.elements['color'];
// You can also easily get the selected value
console.log(radios.value);
// Set the "red" option as the value, i.e. select it
radios.value = 'red';
One might however also select the form via querySelector, which works fine too:
const form = document.querySelector('form[name="somename"]')
However, selecting the radios directly will not work, because it returns a simple NodeList.
document.querySelectorAll('input[name="color"]')
// Returns: NodeList [ input, input ]
While selecting the form first returns a RadioNodeList
document.forms[0].elements['color']
// document.forms[0].color # Shortcut variant
// document.forms[0].elements['complex[naming]'] # Note: shortcuts do not work well with complex field names, thus `elements` for a more programmatic aproach
// Returns: RadioNodeList { 0: input, 1: input, value: "red", length: 2 }
This is why you have to select the form first and then call the elements Method. Aside from all the input Nodes, the RadioNodeList also includes a property value, which enables this simple manipulation.
Reference: https://developer.mozilla.org/en-US/docs/Web/API/RadioNodeList/value
Here is an Example for Radios where no Checked="checked" attribute is used
function test() {
var radios = document.getElementsByName("radiotest");
var found = 1;
for (var i = 0; i < radios.length; i++) {
if (radios[i].checked) {
alert(radios[i].value);
found = 0;
break;
}
}
if(found == 1)
{
alert("Please Select Radio");
}
}
DEMO : http://jsfiddle.net/ipsjolly/hgdWp/2/ [Click Find without selecting any Radio]
Source (from my blog): http://bloggerplugnplay.blogspot.in/2013/01/validateget-checked-radio-value-in.html
Putting Ed Gibbs' answer into a general function:
function findSelection(rad_name) {
const rad_val = document.querySelector('input[name=' + rad_name + ']:checked');
return (rad_val ? rad_val.value : "");
}
Then you can do findSelection("genderS");
lets suppose you need to place different rows of radio buttons in a form, each with separate attribute names ('option1','option2' etc) but the same class name. Perhaps you need them in multiple rows where they will each submit a value based on a scale of 1 to 5 pertaining to a question. you can write your javascript like so:
<script type="text/javascript">
var ratings = document.getElementsByClassName('ratings'); // we access all our radio buttons elements by class name
var radios="";
var i;
for(i=0;i<ratings.length;i++){
ratings[i].onclick=function(){
var result = 0;
radios = document.querySelectorAll("input[class=ratings]:checked");
for(j=0;j<radios.length;j++){
result = result + + radios[j].value;
}
console.log(result);
document.getElementById('overall-average-rating').innerHTML = result; // this row displays your total rating
}
}
</script>
I would also insert the final output into a hidden form element to be submitted together with the form.
I realize this is extremely old, but it can now be done in a single line
function findSelection(name) {
return document.querySelector(`[name="${name}"]:checked`).value
}
I prefer to use a formdata object as it represents the value that should be send if the form was submitted.
Note that it shows a snapshot of the form values. If you change the value, you need to recreate the FormData object. If you want to see the state change of the radio, you need to subscribe to the change event change event demo
Demo:
let formData = new FormData(document.querySelector("form"));
console.log(`The value is: ${formData.get("choice")}`);
<form>
<p>Pizza crust:</p>
<p>
<input type="radio" name="choice" value="regular" >
<label for="choice1id">Regular crust</label>
</p>
<p>
<input type="radio" name="choice" value="deep" checked >
<label for="choice2id">Deep dish</label>
</p>
</form>
If it is possible for you to assign a Id for your form element(), this way can be considered as a safe alternative way (specially when radio group element name is not unique in document):
function findSelection(field) {
var formInputElements = document.getElementById("yourFormId").getElementsByTagName("input");
alert(formInputElements);
for (i=0; i < formInputElements.length; i++) {
if ((formInputElements[i].type == "radio") && (formInputElements[i].name == field) && (formInputElements[i].checked)) {
alert(formInputElements[i].value + ' you got a value');
return formInputElements[i].value;
}
}
}
HTML:
<form action="#n" name="theForm" id="yourFormId">
I like to use brackets to get value from input, its way more clear than using dots.
document.forms['form_name']['input_name'].value;
var value = $('input:radio[name="radiogroupname"]:checked').val();

Automated Form Filling

I’m looking for a way to automate a form.
Here are the details:
Extract a certain number (displayed in its html)
Do some calculations on the extracted number (percentage of that number)
Then automatically fill the remaining input fields with the result instead of typing it out.
This is a common occurrence in forms. The solution depends on what framework / libraries you're using. Assuming you're using none, here is how you might go about it:
https://jsfiddle.net/f52h1smj/1/
rough HTML:
<form>
<label for="number">Number: </label>
<input id="number" type="number" />
<br /> <br />
<label for="calculatedNumber">Calculated Number (50%): </label>
<input id="calculatedNumber" type="number" disabled="true" />
</form>
JS:
(() => {
//get the form element nodes
const $number = document.getElementById("number");
const $calculatedNumber = document.getElementById("calculatedNumber");
//add an event listen to the value you're going to use to pre calculate the other fields
$number.addEventListener("keyup", (e) => {
//it's value is available like so
const value = e.target.value;
//do some validation so that you're calculations don't throw exceptions
if (Number(value) !== 0 && !Number.isNaN(value)) {
//set the value of the other inputs to whatever you like by setting the 'value' property of the node.
$calculatedNumber.value = value / 2;
} else {
$calculatedNumber.value = null;
}
});
})();
These things become a lot simpler in frameworks like React and Angular.

How to put max length on a field using JavaScript?

I've got a working function for empty fields already. Do I need another function to set a max length on these fields or can I edit my current function?
If so how would I fit the max length code in?
Don't use JavaScript to do HTML's job.
<input type="text" name="fname" required maxlength="10" />
To answer your question, you need another function for the max-length. I assume your validateForm method is called at the time of submitting the form. The max-length should be set before submitting the form, preferably when the page loads. As already stated in the comments, setting max-length via the HTML attribute will be the easiest way to do this. Otherwise you need to run a javascript function when the DOM has loaded that basically sets the maxlength attribute for each element, like a.setAttribute('maxlength', '10').
Here is a functional and prettier way to check for all fields. It assumes all field have the same validity requirement.
var maxLength = 8; // or whatever you want
var fieldNames = ["fname","sname","houseno", "ad1", "city", "postcode", "mobno"];
var invalidFields = fieldNames.find(function(fieldName) {
var val = document.getElementById(fieldName).value;
return val == null || val.length == 0 || val.length > maxLength;
});
if (invalidFields.length) {
alert("Please fill ALL Required Fields (no more than " + maxLength + " chars)");
return false;
} else {
return true;
}

Only allow HTML field to start with certain words

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/

JavaScript many input control null or not

I have 350 text inputs in the form. I want to control those for empty or not. I know for one input eg:
var ism=document.getElementById('inputtext').value;
if(ism.length==0){
return false;
}
But I have inputs :
<input type="text" name="inputtext[]"/>
What I do ?
You may want to consider the HTML 5 way; adding the required attribute to prevent form submission with empty inputs
<input type="text" required />
Trying to submit without putting anything in this will cause a message to be shown and submission prevented
Any method you choose should still have server-side validation
You check all of them I suppose ?
var inputs = document.querySelectorAll('[name="inputtext[]"]'),
isEmpty = false;
for (var i=inputs.length; i--;) {
if ( inputs[i].value.length === 0 ) {
isEmpty = true;
break;
}
}

Categories