Develop Reference

Pass text of input to calling function (yes it is possible)

I know this question has been asked -and answered- multiple times. However I found a new solution - but do not fully understand it. The setup is this:
<input id="input1" onchange="GetText()"/>
All answers i found suggest to use the id to get the value of the input.
function GetText(){
alert($("#input1").val());
}
$(this).val() does not work here.
Another way to use the value of the #input1 would be to use this.value in the calling function:
<input id="input1" onchange="GetText(this.value)" />
This passes the value as a parameter to the function.
However I found a JQuery sample that attaches a function to #input1 and makes $(this).val() work.
$("#input1").change(function(e){
alert($(this).val())
});
Against all answers here at stackoverflow seeing that it is possible to attach a function to a input field and have access to the value of it - I ask myself how I would have to write this function and not attach it with JQuery. Or can it be only attached with JQuery? Why?
Here is a fidle with this setup to play

You either pass reference to input object as a parameter in inline call to callback like this:
<input id="input2" onchange="GetText(this)" />
and then in javascript:
function GetText(_this){
alert(_this.value);
}
Fiddle here
Or you can attach function directly to input object like so
document.getElementById('input2').getText = function() {
alert(this.value);
};
and in html:
<input id="input2" onchange="this.getText()" />
Fiddle here
Basically this object in javascript is bound to context, in which the function has been created. When you define function globally, like GetText in your example, this is bound to global object in scope of that function.

<input id="input1" onchange="GetText.call(this)"/>
or
<input id="input1" onchange="GetText.apply(this)"/>
Will call the GetText function with the input as the value of this. Then you can use $(this) or this.value within the scope of GetText.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/call
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply

If you're looking for a similar Vanilla JS function that you can put into you're HTML, which I actually don't recommend, because I support JavaScript HTML separation, it would be something like:
function getInputVal(context){
alert(context.value);
}
In your HTML:
<input id='whoCares' name='whoCares' value='Some Value' onchange='getInputVal(this)' />

Inline JS is not easy to maintain, especially if there's so much of it. It is better to separate your JS and HTML.
//Wait for DOM to load
$(function() {
//set up change event listener --> anonymous function
$('#input1').on('change', function() {
alert( this.value );
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<input id="input1" />
Or if you want to use a named function:
//wait for DOM to load
$(function() {
//Define function
function GetText(){
alert( this.value );
}
//set up change event listener --> named function
$('#input1').on('change', GetText);
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<input type="text" id="input1" />

All answers i found suggest to use the id to get the value of the input.
That's actually a pretty bad design; you want to create event handlers that can be unaware of the elements they're attached to.
The example without using jQuery would look like this:
var input = document.getElementById('input1');
input.addEventListener('change', function(event) {
alert(this.value);
}, false);
<input id="input1" />
See also: addEventListener()

jQuery click function on an array of inputs

I try to implement a change function on every input field named plz_von.
<input type="text" name="plz_von[]" class="plz_von" placeholder="10000">
<input type="text" name="plz_von[]" class="plz_von" placeholder="20000">
<input type="text" name="plz_von[]" class="plz_von" placeholder="30000">
<input type="text" name="plz_von[]" class="plz_von" placeholder="40000">
I want to do it this way:
$('input[name="plz_von[]"]').change(function() {
alert("got it");
});
I don't know what's going wrong. Any idea? I tried it with the class name as well.

Because [ ] is an attribute selector. You need to escape it.
$('input[name="plz_von\\[\\]"]')
Since you have a class that is common, you might as well use that instead.
$('input.plz_von')

Thanks all for the support. Finally I found the failure.
I had to put the jQuery code into the ready function! This is quite clear, because the function cannot by added to the inputfield, when the input field isn't already loaded in the DOM.. grrr
$(document).ready(function() {
$('input[name="plz_von[]"]').change(function() {
alert("hu");
});
});
Best regards,
Marco

Uncaught TypeError: Cannot set property 'value' of null

I'm trying to pass the entered text to the controller using an ajax request. But i'm getting athe error "Uncaught TypeError: Cannot set property 'value' of null " when I tried to execute JS file..
Here is the HTMLcode:
<form action="">
<input type="text" class="searchbox1" name="search" placeholder="Search for Brand, Store or an Item..." value="text" />
<input type="button" class="searchbox_submit1" name="submit" value="text" onClick="javascript:getSearchText();">
</form>
Here is the JS code:
function getSearchText() {
var searchText = document.getElementByName("search").value;
h_url=document.getElementById("u").value;
var theURL = h_url+'search_all/' + deptid + '/' + searchText + '/1';
$.ajax({
url : theURL,
fail: function(){
},
success : function() {
},
error:function(){
}
});
}
Please help me to fix this.

You don't have an element with the id u.That's why the error occurs.
Note that you are trying to get the value of the input element with the name 'u' and it's not defined in your code.

The problem may where the code is being executed. If you are in the head of a document executing JavaScript, even when you have an element with id="u" in your web page, the code gets executed before the DOM is finished loading, and so none of the HTML really exists yet... You can fix this by moving your code to the end of the page just above the closing html tag. This is one good reason to use jQuery.

In case anyone landed on this page for a similar issue, I found that this error can happen if your JavaScript is running in the HEAD before your form is ready. Moving your JavaScript to the bottom of the page fixed it for my situation.

The problem is that you haven't got any element with the id u so that you are calling something that doesn't exist.
To fix that you have to add an id to the element.
<input id="u" type="text" class="searchbox1" name="search" placeholder="Search for Brand, Store or an Item..." value="text" />
And I've seen too you have added a value for the input, so it means the input is not empty and it will contain text. As result placeholder won't be displayed.
Finally there is a warning that W3Validator will say because of the "/" in the end. :
For the current document, the validator interprets strings like according to legacy rules that break the expectations of most authors and thus cause confusing warnings and error messages from the validator. This interpretation is triggered by HTML 4 documents or other SGML-based HTML documents. To avoid the messages, simply remove the "/" character in such contexts. NB: If you expect <FOO /> to be interpreted as an XML-compatible "self-closing" tag, then you need to use XHTML or HTML5.
In conclusion it says you have to remove the slash. Simply write this:
<input id="u" type="text" class="searchbox1" name="search" placeholder="Search for Brand, Store or an Item...">

I knew that i am too late for this answer, but i hope this will help to other who are facing and who will face.
As you have written h_url is global var like var = h_url; so you can use that variable anywhere in your file.
h_url=document.getElementById("u").value;
Here h_url contain value of your search box text value whatever user has typed.
document.getElementById("u");
This is the identifier of your form field with some specific ID.
Your Search Field without id
<input type="text" class="searchbox1" name="search" placeholder="Search for Brand, Store or an Item..." value="text" />
Alter Search Field with id
<input id="u" type="text" class="searchbox1" name="search" placeholder="Search for Brand, Store or an Item..." value="text" />
When you click on submit that will try to fetch value from document.getElementById("u").value; which is syntactically right but you haven't define id so that will return null.
So, Just make sure while you use form fields first define that ID and do other task letter.
I hope this helps you and never get Cannot set property 'value' of null Error.

guys This error because of Element Id not Visible from js Try to inspect element from UI and paste it on javascript file:
before :
document.getElementById('form:salesoverviewform:ticketstatusid').value =topping;
After :
document.getElementById('form:salesoverviewform:j_idt190:ticketstatusid').value =topping;
Credits to Divya Akka .... :)

It seems to be this function
h_url=document.getElementById("u").value;
You can help yourself using some 'console.log' to see what object is Null.

h_url=document.getElementById("u") is null here
There is no element exist with id as u

Add defer to your script tag, if it's in header. It will allow your script to execute after the DOM is loaded.
<script src="script.js type="text/javascript"></script>
It should look like this:
<script src="script.js type="text/javascript" defer></script>

Jquery Setting Value of Input Field

I have an input field and i am trying to set its value using its class
<form:input path="userName" id="userName" title="Choose A Unique UserName" readonly="${userNameStatus}" class="formData"/>
Which renders as:
<input id="userName" name="userName" title="Choose A Unique UserName" class="formData" type="text" value=""/>
I am using the following jquery but this does not seem to work. Can someone tell me where i am going wrong.
$(".formData").html("");
Edited JQuery Function that handles the event
$('#reset').click(function (){
$("#userNameErr").text("");
$('#badgeNoErr').text("");
$(".errors").html("");
$(".formData").val("");
});
nor is $(".formData").text("") or $(".formData").val("") working.

This should work.
$(".formData").val("valuesgoeshere")
For empty
$(".formData").val("")
If this does not work, you should post a jsFiddle.
Demo:
$(function() {
$(".resetInput").on("click", function() {
$(".formData").val("");
});
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="text" class="formData" value="yoyoyo">
<button class="resetInput">Click Here to reset</button>

If the input field has a class name formData use this :
$(".formData").val("data")
If the input field has an id attribute name formData use this :
$("#formData").val("data")
If the input name is given use this :
$("input[name='formData']").val("data")
You can also mention the type. Then it will refer to all the inputs of that type and the given class name:
$("input[type='text'].formData").val("data")

change your jquery loading setting to onload in jsfiddle . . .it works . . .

use this code for set value in input tag by another id.
$(".formdata").val(document.getElementById("fsd").innerHTML);
or
use this code for set value in input tag using classname="formdata"
$(".formdata").val("hello");

You just write this script. use input element for this.
$("input").val("valuesgoeshere");
or by id="fsd" you write this code.
$("input").val(document.getElementById("fsd").innerHTML);

$('.formData').attr('value','YOUR_VALUE')

Put your jQuery function in
$(document).ready(function(){
});
It's surely solved.

Setting HTML textbox value using javascript function?

I'm using this code to set the HTML textbox value using Javascript function. But it seems to be not working. Can anyone point out, what is wrong with this code?
Whats your Name?
<input id="name" value="" />
<script type="text/javascript">
function setValue(value){
var myValue=value;
document.getElementsById("name").value = myValue;
}
</script>
the "value" is came from my android java class using this codes
String value = "Isiah";
WebView web = (WebView) findViewById(R.id.web1);
web.getSettings().setJavaScriptEnabled(true);
web.loadUrl("file:///android_asset/www/webpage");
web.loadUrl("javascript:setValue("+ value +")");

function setValue(value) {
var myValue=value; //unnecessary
document.getElementById("name").value= myValue;
}
But then as pointed out in the comments, you need to call setValue(value) somewhere in your code. Right now you just defined the function is never called.

You could either access the element’s value by its name:
document.getElementsByName("textbox1"); // returns a list of elements with name="textbox1"
document.getElementsByName("textbox1")[0] // returns the first element in DOM with name="textbox1"
So:
input name="buttonExecute" onclick="execute(document.getElementsByName('textbox1')[0].value)" type="button" value="Execute" />
Or you assign an ID to the element that then identifies it and you can access it with getElementById:
<input name="textbox1" id="textbox1" type="text" />
<input name="buttonExecute" onclick="execute(document.getElementById('textbox1').value)" type="button" value="Execute" />

You are using document.getElementsById("name") it should be document.getElementById("name")
not Elements it is Element

You are not linking the function to anything. For example, a click:
<input id="name" value="" onclick="javascript:this.value=12;"/>
Replace the onclick attribute for your desired function, whatever it does (you need to be more specific)
Also, there is no language attribute (at least not anymore) use type="text/javascript" instead
Here is a fiddle: http://jsfiddle.net/4juEp/
Click the input to see it working.
Look at this second fiddle. http://jsfiddle.net/4juEp/1/
which loads whatever is defined in the hid input to the name input.

Firstly, you have a typo in your javascript function i.e. you have used getElementsById as compared to getElementById
To set the value of the textbox on page load, I suggest you use an alternative
<body onload="setValue('yourValueToSet');">
<!-- Your usual html code in the html file -->
</body>

I think you are missing the quotes,
try,
web.loadUrl("javascript:setValue('"+ value +"')");
also consider about the typo.

Check this out:
<body onload="setvalue($value);">
Whats your Name?<input id="name" name="name" value=""/>
<script type="text/javascript">
function setValue(value){
document.{formname}.name.value = value;}</script>

It's not Elements
It's Element
You should use document.getElementById('object-id');