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toggle checkbox with javascript

I want to uncheck a checkbox using javascript. I have one button which just unchecks the box and works fine:
function clear() {
document.getElementById("check").checked = "";
}
I have another button that I want to check the box if not checked and uncheck if it is. Below doesn't uncheck the box. I can can switch the if statement and does works the opposite way. What's the problem?
function switchIt() {
if (document.getElementById("check").checked !== "checked") {
document.getElementById("check").checked = "checked";
} else {
document.getElementById("check").checked = "";
}
Thanks!

switch is a reserved word, use another one
function switchIt() {
var box = document.getElementById("check");
if (box.checked) {
box.checked = false;
} else {
box.checked = true;
}
}
setInterval(switchIt, 1000);
<input type="checkbox" id="check" />

Treat "checked" as a boolean, not as a string.
You can just invert it, as in
element = document.getElementById("check")
element.checked = !element.checked
A more featured example:
var $toggle = document.getElementById('toggle');
var $checkbox = document.getElementById('checkbox');
var toggle_checkbox = function() {
$checkbox.checked = !checkbox.checked;
}
$toggle.addEventListener('click',toggle_checkbox);
<label>
Checkbox:
<input id="checkbox" type="checkbox" checked />
</label>
<button id="toggle">Toggle</button>

You need a boolean to do that.
Take a look at this pen:
https://codepen.io/anon/pen/jJyXgO
let checkbox = document.querySelectorAll('#check')[0]
setInterval(function() {
checkbox.checked = !checkbox.checked
}, 1000)

I've never seen it done with a string "checked" before. Try with a boolean like:
function change() {
if (document.getElementById("check").checked !== true) {
document.getElementById("check").checked = true;
} else {
document.getElementById("check").checked = false;
}
}
or easier
function change() {
document.getElementById("check").checked = !document.getElementById("check").checked
}
Don't forget, switch is reserved, so use a different name, as I did with change()

Stop form submission if radio button is checked

I have a form on FormAssembly, and I would like to stop someone submitting the form if they select the 'No' Radio Button for the question 'Are you an employer?'. I have put what I have so far in a jsfiddle.
JS:
$(document).ready(function() {
$('input#tfa_1904').click(function() {
if ($('#tfa_1904').is(':checked') {
submitButton.disabled = true;
}
else {
submitButton.disabled = false;
}
});
});
submitButton code:
document.addEventListener("DOMContentLoaded", function() {
var warning = document.getElementById("javascript-warning");
if (warning != null) {
warning.parentNode.removeChild(warning);
}
var oldRecaptchaCheck = parseInt('0');
if (oldRecaptchaCheck !== -1) {
var explanation = document.getElementById('disabled-explanation');
var submitButton = document.getElementById('submit_button');
if (submitButton != null) {
submitButton.disabled = true;
if (explanation != null) {
explanation.style.display = 'block';
}
}
}
});

In your case you don't need to check whether the radio button is checked as only one will be checked at a time. So, just capturing the click will suffice.
$(document).ready(function() {
$('input#tfa_1904').click(function() {
$('#submit_button').prop('disabled', true);
});
$('input#tfa_1903').click(function() {
$('#submit_button').prop('disabled', false);
});
});
Updated fiddle:
https://jsfiddle.net/h5r8gud1/8/

jquery return false killed submit event?

I try to use loop to validate each of every input whether they are filled or not. But end up my submit_form function doesn't get triggered.
$('#submit').click(function(){
var hold = true;
if ($('.tab2').hasClass('active') && hold == true) {
$('.tab-content:visible input').each(function(i, val) {
if ($(this).val() == '') {
alert("Please fill in valid " + $(this).attr('data-error'));
$(this).focus();
hold = true;
return false;
} else {
hold = false;
}
});
return false; //can't remove this
}
submit_form(); //not triggered although all inputs are filled
})
if I removed the return false, there will be no checking..

See if check box is clicked until it is clicked

I am seeing how I can make an Are You Human checkbox, but I am having a problem (Code At The End). I am trying to make it see if it is clicked until it is clicked. I tried onclick, but that is not working.
window.onload = function() {
var input = document.getElementById('ruhuman');
function check() {
if (input.checked) {
ruhuman.checked = true;
if (event.originalEvent === undefined) {
ruhuman.human = false;
} else {
ruhuman.human = true;
}
}
alert(ruhuman.human);
alert(ruhuman.checked);
}
input.onchange = check;
check();
}
<input type="checkbox" id="ruhuman" class="ruhuman" onclick="check()" required="required">
<label>R U Human?</label>
Edit: Thanks for your help! Finished product at http://ruhuman.github.io/.
To the people that answered I can put your github for your help!

originalEvent is JQuery, not JavaScript. A workaround is to test screenX and screenY -- if it's a human, these will have some value based on the checkbox position. Also, you can remove the onclick from your html and tie your click event like this:
document.getElementById ("ruhuman").addEventListener("click", function(e){
if (this.checked) {
ruhuman.checked = true;
if (e.screenX && e.screenY) {
ruhuman.human = true;
} else {
ruhuman.human = false;
}
}
console.log(ruhuman.human);
console.log(ruhuman.checked);
});
JS Fiddle Demo

This works: https://jsfiddle.net/rz4pmp5L/3/
var input = document.getElementById('ruhuman');
var ruhuman =
{
checked: false
};
function check()
{
if (input.checked)
{
ruhuman.checked = true;
}
alert(ruhuman.checked);
}
input.onchange = check;
check();
The problem was (at least) that ruhuman was not defined at all.

Javascript check if radio button was checked?

I have found scripts that do it, but they only work with one radio button name, i have 5 different radio button sets. How can i check if its selected right now i tried on form submit
if(document.getElementById('radiogroup1').value=="") {
alert("Please select option one");
document.getElementById('radiogroup1').focus();
return false;
}
does not work.

If you have your heart set on using standard JavaScript then:
Function definition
var isSelected = function() {
var radioObj = document.formName.radioGroupName;
for(var i=0; i<radioObj.length; i++) {
if( radioObj[i].checked ) {
return true;
}
}
return false;
};
Usage
if( !isSelected() ) {
alert('Please select an option from group 1 .');
}
I'd suggest using jQuery. It has a lot of selector options which when used together simplify the much of the code to a single line.
Alternate Solution
if( $('input[type=radio][name=radioGroupName]:selected').length == 0 ) {
alert('Please select an option from group 1 .');
}

var checked = false, radios = document.getElementsById('radiogroup1');
for (var i = 0, radio; radio = radios[i]; i++) {
if (radio.checked) {
checked = true;
break;
}
}
if (!checked) {
alert("Please select option one");
radios.focus();
return false;
}
return true;

A very simple function is:
<script type="text/javascript">
function checkRadios(form) {
var btns = form.r0;
for (var i=0; el=btns[i]; i++) {
if (el.checked) return true;
}
alert('Please select a radio button');
return false;
}
</script>
<form id="f0" onsubmit="return checkRadios(this);">
one<input type="radio" name="r0"><br>
two<input type="radio" name="r0"><br>
three<input type="radio" name="r0"><br>
<input type="submit">
</form>
However, you sould always have one radio button selected by default (i.e. with the select attribute), some user agents may automatically select the first button. Then you just need to check if the default (usually the first one) is checked or not.

Why don't just use a oneliner?
I wrote this code, it will submit the form if at least one radio is checked:
(function(el){for(var i=el.length;i--;) if (el[i].checked) return el[i].form.submit()||1})(document.form_name.radio_name)||alert('please select item')
Otherwise it will make an alert. Or you may also modify it to use with form's onsubmit:
return (function(el){for(var i=el.length;i--;) if (el[i].checked) return 1})(document.form_name.radio_name)||alert('please select item')
Just replace form_name and radio_name accordingly.
See how it works: http://jsfiddle.net/QXeDv/5/

Here's a good tutorial -> http://www.somacon.com/p143.php
// return the value of the radio button that is checked
// return an empty string if none are checked, or
// there are no radio buttons
function getCheckedValue(radioObj) {
if(!radioObj) return "";
var radioLength = radioObj.length;
if(radioLength == undefined)
if(radioObj.checked) return radioObj.value;
else return "";
for(var i = 0; i < radioLength; i++) {
if(radioObj[i].checked) return radioObj[i].value;
}
return "";
}
// set the radio button with the given value as being checked
// do nothing if there are no radio buttons
// if the given value does not exist, all the radio buttons
// are reset to unchecked
function setCheckedValue(radioObj, newValue) {
if(!radioObj) return;
var radioLength = radioObj.length;
if(radioLength == undefined) {
radioObj.checked = (radioObj.value == newValue.toString());
return;
}
for(var i = 0; i < radioLength; i++) {
radioObj[i].checked = false;
if(radioObj[i].value == newValue.toString()) radioObj[i].checked = true;
}
}

Are you ok with jquery? If so:
$(document).ready(function(){
if($('input[type=radio]:checked').length == 0)
{
alert("Please select option one");
document.getElementById('radiogroup1').focus();
return false;
}
}