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Get the id of input using it's name

I want to get the id of input using it's name,and to empty the input field.But it's not working.Is it possible?
html:
<input type="text" id="1" name="Color" maxlength="2" />
jQuery:
var myId="#";
myId=myId + $('[name="Color"]').attr('id');
$($myId).var('');

You can do this:
let id = $('input[name$="Color"]').val('').attr('id');
console.log(id);
$(`#${id}`).val('');
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="text" id="1" name="Color" maxlength="2" />

You can set the input value using the val() function.
<input type="text" id="1" name="Color" maxlength="2"/>
var myId='#' + $('[name="Color"]').attr('id');
$(myId).val('');
To get the input value use it like this:
$(myId).val();

Try this code.
const myId = $('input[name="Color"]').attr('id');
$("#"+myId).val(''); // you can set any value here or you can perform any other operations on this element -> $("#"+myId)
On first line of this JS code, we are getting id attribute and then on second line, we're using to manipulate element.
Now, if you want id only for performing some operations on that input element, you don't need to get id. You can also do like this.
let elem = $('input[name="Color"]');
elem.val(''); // only if same name is not used anywhere else.
I hope this helps you.

You can use attr directly to set a value. Moreover there is no need to append #.
let element = $('[name="Color"]');
console.log("before", element.attr('id'));
element.attr('id', null);
console.log("after", element.attr('id'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="text" id="1" name="Color" maxlength="2" />

Update <input> value onchange

I have bunch of inputs like:
<input />
<input />
<input />
and a button which ads extra input
<button>Add Input</button>
The issue is that when a user put the text in the input(s) and add
additional input afterwards (i.e. press Add Input) the entered text in old inputs disappears.
JSFiddle:
<div id="inputs"></div>
<button onclick="document.getElementById('inputs').innerHTML += '<input /><br>'">Add Input</button>
So I decided to update <input> value attribute. I have tried with onchange but had no luck.
The code with errors and trials is super simple and looks like:
function change_value(el) {
document.getElementById('some-id').value = el.value
}
<input id="some-id" value="${this.value}" onchange="change_value(this)" />
Will be grateful for any suggestions about how to keep <input value up-to-date with user text.

It depends on what content you want to update. You can find a snippet below, that works oninput and updates the textContent of a span.
const input = document.getElementById('some-id')
const display = document.getElementById('updated')
input.addEventListener('input', function(e) {
display.textContent = this.value
})
<input id="some-id" value="" /><br /><br />
<div>Updated value: <span id="updated"></span></div>
EDIT
A new snippet may clear things up a bit.
const btnAdd = document.getElementById('add')
btnAdd.addEventListener('click', function(e) {
var input = document.createElement('input');
input.type = "text";
document.getElementById('inputs').appendChild(input)
})
<div id="inputs"></div>
<button id="add">Add Input</button>
Use createElement() instead of innerHTML.

Try using innerHtml like this
document.getElementById('some-id').innerHtml instead of value
https://www.w3schools.com/js/js_htmldom_html.asp

Actually, it is not possible this way, maybe with some tricks like with any change store the value and create new input with the new value or change the innerHtml, maybe it works.

Run function after a checkbox change on my page

I have dynamically created check boxes on my page and assigned each of them an unique id like 'renameteam1', 'renameteam2' etc.. I am trying to run a function when one of these gets checked. The function will then allow the user to enter a corresponding field that was previously readonly.
I have tried the following but it doesn't seem to be working.
var a=0;
$('input[type=checkbox]').change(function () {
for (var i=0;i<rows3;i++){
a=a+1;
var id= '#renameteam'+a;
if ($(id).is(":checked")) {
$('#newname'+a).removeProp('readonly');
}
}
//Here do the stuff you want to do when 'unchecked'
});
Any Suggestions?

This is how I would do it
//delegate the event so you can call this on document ready and it will still be bound to any dynamically created elements
$(document).on('change', 'input[type=checkbox]', function() {
var checkbox = $(this),
otherInput = $('#' + checkbox.data('id'));
otherInput.prop('readonly', !checkbox.is(':checked'));
if (!checkbox.is(':checked')) {
// do stuff here when checkbox isn't checked - not sure if you still want this bit but it is as per your comments in the code above
}
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="checkbox" name="checkbox" value="" id="renameteam1" data-id="newname1" />
<!-- use a data attribute to target the id of the input you want to make readonly -->
<input type="textbox" name="textbox" value="" id="newname1" readonly />
If you don't want to use a data attribute, you could do this:
//delegate the event so you can call this on document ready and it will still be bound to any dynamically created elements
$(document).on('change', 'input[type=checkbox]', function() {
var checkbox = $(this),
otherInput = $('#newname' + this.id.replace('renameteam', ''));
otherInput.prop('readonly', !checkbox.is(':checked'));
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="checkbox" name="checkbox" value="" id="renameteam1" />
<!-- use a data attribute to target the id of the input you want to make readonly -->
<input type="textbox" name="textbox" value="" id="newname1" readonly />

Try using an on click instead of on change for checkboxes and radio buttons.

Click button to get value from nearby input?

I have a button that comes after an input in the HTML, and I want to use that button to retrieve the value from that input and perform an action. The problem I'm facing is that my jQuery isn't finding that value.
The HTML:
<div>
<input class="an-input" type="text"></input>
<button class="ui-state-default inputButton an-button">GO</button>
</div>
The JS:
$('.an-button').click(function() {
var inputValue = $('.an-button').prev('.an-input').find('input').val();
window.open('http://a810-bisweb.nyc.gov/bisweb/JobsQueryByNumberServlet?passjobnumber='+inputValue+'&passdocnumber=&go10=+GO+&requestid=0');
});

Travel up the DOM with closest:
var inputValue = $('.an-button').closest('div').find('input').val();
Fiddle

Try removing .find('input') , as .prev(".an-input") should return input element . Also note, <input /> tag is self-closing
$(".an-button").click(function() {
var inputValue = $(this).prev(".an-input").val();
console.log(inputValue)
//window.open('http://a810-bisweb.nyc.gov/bisweb/JobsQueryByNumberServlet?passjobnumber='+inputValue+'&passdocnumber=&go10=+GO+&requestid=0');
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js">
</script>
<div>
<input class="an-input" type="text" />
<button class="ui-state-default inputButton an-button">GO</button>
</div>

To target a sibling, it must be of similar type.
Try this instead:
$('.an-button').click(function() {
var inputValue = $('.an-button').parent().find('.an-input').val();
window.open('http://a810-bisweb.nyc.gov/bisweb/JobsQueryByNumberServlet?passjobnumber='+inputValue+'&passdocnumber=&go10=+GO+&requestid=0');
});

$('button.an-button').click(function() {
var inputValue = $('.an-input:text').val();
... rest of code
})

The input element has not end tag
more information here
the correct is <input />

retrieving text field value using javascript

I want to retrieve textfield value using javascript. suppose i have a code like:
<input type='text' name='txt'>
And I want to retrieve it using javascript. I call a function when a button is clicked:
<input type='button' onclick='retrieve(txt)'>
What coding will the retrieve function consist of?

You can do this:
Markup:
<input type="text" name="txt" id="txt"/>
<input type="button" onclick="retrieve('txt');"/>
JavaScript:
function retrieve(id) {
var txtbox = document.getElementById(id);
var value = txtbox.value;
}

Let's say you have an input on your page with an id of input1, like this:
<input type="text" id="input1" />
You first need to get the element, and if you know the Id, you can use document.getElementById('input1'). Then, just call .value to get the value of the input box:
var value = document.getElementById('input1').value;
Update
Based on your markup, I would suggest specifying an id for your text box. Incase you don't have control over the markup, you can use document.getElementsByName, like so:
var value = document.getElementsByName('txt')[0].value;

One of the way is already explained by Andrew Hare.
You can also do it by entering the value in the textbox and getting a prompt box with entered message when a user click the button.
Let's say, you have a textbox and a input button
<input type="text" name="myText" size="20" />
<input type="button" value="Alert Text" onclick="retrieve()" />
The function for retrieve()
function retrieve()
{
var text = document.simpleForm.myText.value;
alert(text);
}