We Keep Coding

How to wait before evaluating an input field

I've got a field for a product that its quantity is dependant on another product's quantity (cant be less than 70%, or more than 100%). Thing is, it evaluates it so quiclky that if the main field is '100', I cant enter 75 on the other field, because I first need to enter the '7', and my code considers it less than 70% and instantly changes it to the 70% value.
I've already tried using a self-made 'sleep' function, that makes a promise take some time to resolve.
setInterval and setTimeout also do not work as I intend for some reason (only evaluates the dependent field when I press enter, and it is not after the stablished time). This is not consistent with the rest of the table, so it is not a suitable solution.
This is the angular bit that controls this input
<div class="input-field">
<input class="input" type="number" [integerInput] ="true"
[disabled] ="item.deshabilitado( ) || !editable"
[(ngModel)] ="item.cantidad"
[ngModelOptions]="{standalone: true}"
(keyup) ="setCantidad( item, $event.target.value )"
max="9999" min="1" value="1" >
</div>
Sadly I cant get a minimal and working example. I need the dependent field to be able to evaluate its value automatically (without pressing enter or clicking on another field) without automatically correcting my input when I press only one character.

Use blur() method instead of keyup(). I guess you are validating the input with keyup() and each time you enter value it validates. For instance you are trying to enter 70 but when you enter first character, 7 it is invalid. The blur() fires your method and validates your input when you are done with inputting value.
<div class="input-field">
<input class="input" type="number" [integerInput]="true"
[disabled]="item.deshabilitado( ) || !editable"
[(ngModel)]="item.cantidad"
[ngModelOptions]="{standalone: true}"
(focusout)="setCantidad( item, $event.target.value )"
max="9999" min="1" value="1" >
</div>
In addition, you can use keyup.enter if a user is done with inputting value and presses enter. The value updates when the enter key is pressed or clicked somewhere else.

UPDATE:
I was able to solve this and get it to work like I intended at the beginning. The resulting code for the field I tried to validate would be
debounce (afterValueChanged)="setCantidad( item )"
It behaves in a way that does not need me to click outside the field for it to start validating, instead of the (blur) or (focusout)

Try to use the debounce function
Import debounceTime from rxjs and use it to add some delay :)
Check out this example

In the other field where you are trying to enter 75, you can add an ngModelOptions configuration to update only on blur.
[ngModelOptions]="{ updateOn: 'blur' }"
By default it updates on 'change', which explains the current behavior.
Update
You could also debounce the input using RXJS. This is probably closer to what you were trying to do with setInterval / setTimeout. This is also a use case where Reactive Forms really shines over Template Driven Forms imo, since you'll need to use RXJS operators.
For reactive driven forms, you just pipe an operator before subscribing to the valueChanges observable of the formControl
this.myInput.valueChanges
.pipe(
debounceTime(1000), // add 1 second of delay
distinctUntilChanged() // optional but recommended - only trigger for new values
)
.subscribe(val=> {
console.log('value', val);
});
It is possible to accomplish the same behavior in template driven forms but there is some setup involved. See this SO question/answer

As per the information given, you might want to debounce your function call.
Debounced functions do not execute when invoked, they wait for a pause of invocations over a configurable duration before executing; each new invocation restarts the timer.
<div class="input-field">
<input class="input" type="number" [integerInput] ="true"
[disabled] ="item.deshabilitado( ) || !editable"
[ngModel] ="item.cantidad"
[ngModelOptions]="{standalone: true}"
(keyup) ="setCantidad( item, $event.target.value )"
max="9999" min="1" value="1" >
</div>
In your component class:
timer;
setCantidad(item,value){
if(this.timer){
clearTimeout(this.timer);
}
this.timer = setTimeout(() => {
this.item.cantidad = value;
//perform any operations here
console.log(item, value);
},1000);
}
This will wait for the user to stop typing and execute the operation after the specified time in the timeout.
Note: One additional change, if you want to render the value in the same input field where you are typing, consider changing the [(ngModel)] -> [ngModel].
This will just perform a property binding and not event binding.
Demo stackblitz link : https://stackblitz.com/edit/angular-cu9gss

Javascript - Display input inside div

So this is probably an easy one, but I'm just not doing it right. My goal is to send the user input from this textbox:
<input type='text' placeholder='Form Name...' id='formNameInput' required>
Into this Div:
<div id="code_output"></div>
I'm trying to make it appear in real time, and so far I used this to try and do so, but it doesn't work:
document.getElementById("code_output").innerHTML += document.getElementById("formNameInput").value;
Why doesn't it show? Does my code need something to trigger the Javascript?

You're close, but the issue is that you're not using an event handler. The script is executing your code once, as soon as possible (before you have the chance to enter anything into the text input). So, you have to add some sort of event listener so that the copying happens at the appropriate time. Something like below:
document.getElementById('formNameInput').addEventListener('keyup', copyToDiv);
function copyToDiv() {
document.getElementById("code_output").innerHTML = document.getElementById("formNameInput").value;
}
<input type='text' placeholder='Form Name...' id='formNameInput' required>
<div id="code_output"></div>

You need to do that whenever the value of formNameInput changes. For that you need an event.
Your code should look like:
document.getElementById("formNameInput").addEventListener('input', function () {
document.getElementById("code_output").innerHTML += this.value;
});

function change() {
document.getElementById("code_output").innerHTML = document.getElementById("formNameInput").value;
}
document.getElementById('formNameInput').onkeyup = change
maybe this is what you are trying?

You need to attach an event listener to your input that executes a function any time an input event occurs on the field:
formNameInput.addEventListener('input', function(e) {
code_output.textContent = e.target.value
})
<input type="text" placeholder="Form Name..." id="formNameInput" required />
<div id="code_output"></div>
Please note that the above code takes advantage of the fact that browsers automatically create a global variable for each element with a unique id attribute value, and this variable has the same name as the value of the id.
If the concept of events is new to you, this might be a good place to get started:
https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Building_blocks/Events

overwrite range slider values using javascript

I am using a range slider with text box, so whenever I slide the range, the value gets updated in the textbox. Also whenever I change the value in the textbox, the slider will move accordingly.
Here is the code I am using:
$('input[type="range"]').on('input change', function() {
$('#LoanAmntText').val($(this).val());
});
$('#LoanAmntText').keyup(function(e) {
var val = $(this).val().replace(/[^\d\+]/g, ""); // check only for digits
$('#LoanAmntRange').val(val).trigger("change");
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="range" min="0" max="20000000" step="100000" value="4000000" id="LoanAmntRange" class="LoanAmntRange">
<input type="text" id="LoanAmntText" />
The slider's min, max and step values are used in a way that it will cover most common values while using the range slider. But when I use the textbox to enter the value, I would like to use any number starting from 0( for ex:I need to enter 2450003).But with current code, it's not allowing me to do so.
What will be the best way to achieve this?
Fiddle:https://jsfiddle.net/anoopcr/cy14pu1L/11/

Your keyup event will trigger after every key press. Since your slider has a step size of 100000 no one digit will able to comply with that. Either change your step size to 1 or use the change event instead.

In Vanilla JS - Change a variable once a user finishes typing

Without using jQuery - I am trying to simply change a var based on a input's value - when the user finishes typing then update the div value. Is there a way to do it without writing a function to fire onchange? Something like if a change happen change var.
<div>
<input type="text" maxlength="12" id="inNum" />
</div>
<div id="rooms"></div>
var disNum = document.getElementById('inNum').onchange;
document.getElementById('rooms').innerHTML = disNum.value;

The best way is to listen to one of keypress, keydown or keyup.
I tried listening to onchange but that would only fire when the input was blurred; maybe this is your current problem, or actually your desired behaviour. If this is your desired behaviour, just replace .onkeyup below with .onchange.
The only other way you could do this (that I can think of) is by using some setInterval loop, and re-checking the state in each iteration, but really, that would be a terrible idea.
Here, I've made a JSFiddle to demonstrate my approach.
var disNum = document.getElementById('inNum');
disNum.onkeyup = function(){
document.getElementById('rooms').innerHTML = disNum.value;
};
<div>
<input type="text" maxlength="12" id="inNum">
</div>
<div id="rooms"></div>

html <input type="text" /> onchange event not working

I am trying to do some experiment. What I want to happen is that everytime the user types in something in the textbox, it will be displayed in a dialog box. I used the onchange event property to make it happen but it doesn't work. I still need to press the submit button to make it work. I read about AJAX and I am thinking to learn about this. Do I still need AJAX to make it work or is simple JavaScript enough? Please help.
index.php
<script type="text/javascript" src="javascript.js"> </script>
<form action="index.php" method="get">
Integer 1: <input type="text" id="num1" name="num1" onchange="checkInput('num1');" /> <br />
Integer 2: <input type="text" id="num2" name="num2" onchange="checkInput('num2');" /> <br />
<input type="submit" value="Compute" />
</form>
javascript.js
function checkInput(textbox) {
var textInput = document.getElementById(textbox).value;
alert(textInput);
}

onchange is only triggered when the control is blurred. Try onkeypress instead.

Use .on('input'... to monitor every change to an input (paste, keyup, etc) from jQuery 1.7 and above.
For static and dynamic inputs:
$(document).on('input', '.my-class', function(){
alert('Input changed');
});
For static inputs only:
$('.my-class').on('input', function(){
alert('Input changed');
});
JSFiddle with static/dynamic example: https://jsfiddle.net/op0zqrgy/7/

HTML5 defines an oninput event to catch all direct changes. it works for me.

Checking for keystrokes is only a partial solution, because it's possible to change the contents of an input field using mouse clicks. If you right-click into a text field you'll have cut and paste options that you can use to change the value without making a keystroke. Likewise, if autocomplete is enabled then you can left-click into a field and get a dropdown of previously entered text, and you can select from among your choices using a mouse click. Keystroke trapping will not detect either of these types of changes.
Sadly, there is no "onchange" event that reports changes immediately, at least as far as I know. But there is a solution that works for all cases: set up a timing event using setInterval().
Let's say that your input field has an id and name of "city":
<input type="text" name="city" id="city" />
Have a global variable named "city":
var city = "";
Add this to your page initialization:
setInterval(lookForCityChange, 100);
Then define a lookForCityChange() function:
function lookForCityChange()
{
var newCity = document.getElementById("city").value;
if (newCity != city) {
city = newCity;
doSomething(city); // do whatever you need to do
}
}
In this example, the value of "city" is checked every 100 milliseconds, which you can adjust according to your needs. If you like, use an anonymous function instead of defining lookForCityChange(). Be aware that your code or even the browser might provide an initial value for the input field so you might be notified of a "change" before the user does anything; adjust your code as necessary.
If the idea of a timing event going off every tenth of a second seems ungainly, you can initiate the timer when the input field receives the focus and terminate it (with clearInterval()) upon a blur. I don't think it's possible to change the value of an input field without its receiving the focus, so turning the timer on and off in this fashion should be safe.

onchange only occurs when the change to the input element is committed by the user, most of the time this is when the element loses focus.
if you want your function to fire everytime the element value changes you should use the oninput event - this is better than the key up/down events as the value can be changed with the user's mouse ie pasted in, or auto-fill etc
Read more about the change event here
Read more about the input event here

use following events instead of "onchange"
- onkeyup(event)
- onkeydown(event)
- onkeypress(event)

Firstly, what 'doesn't work'? Do you not see the alert?
Also, Your code could be simplified to this
<input type="text" id="num1" name="num1" onkeydown="checkInput(this);" /> <br />
function checkInput(obj) {
alert(obj.value);
}

I encountered issues where Safari wasn't firing "onchange" events on a text input field. I used a jQuery 1.7.2 "change" event and it didn't work either. I ended up using ZURB's textchange event. It works with mouseevents and can fire without leaving the field:
http://www.zurb.com/playground/jquery-text-change-custom-event
$('.inputClassToBind').bind('textchange', function (event, previousText) {
alert($(this).attr('id'));
});

A couple of comments that IMO are important:
input elements not not emitting 'change' event until USER action ENTER or blur await IS the correct behavior.
The event you want to use is "input" ("oninput"). Here is well demonstrated the different between the two: https://javascript.info/events-change-input
The two events signal two different user gestures/moments ("input" event means user is writing or navigating a select list options, but still didn't confirm the change. "change" means user did changed the value (with an enter or blur our)
Listening for key events like many here recommended is a bad practice in this case. (like people modifying the default behavior of ENTER on inputs)...
jQuery has nothing to do with this. This is all in HTML standard.
If you have problems understanding WHY this is the correct behavior, perhaps is helpful, as experiment, use your text editor or browser without a mouse/pad, just a keyboard.
My two cents.

onkeyup worked for me. onkeypress doesn't trigger when pressing back space.

It is better to use onchange(event) with <select>.
With <input> you can use below event:
- onkeyup(event)
- onkeydown(event)
- onkeypress(event)

when we use onchange while you are typing in input field – there’s no event. But when you move the focus somewhere else, for instance, click on a button – there will be a change event
you can use oninput
The oninput event triggers every time after a value is modified by the user.Unlike keyboard events, it triggers on any value change, even those that does not involve keyboard actions: pasting with a mouse or using speech recognition to dictate the text.
<input type="text" id="input"> oninput: <span id="result"></span>
<script>
input.oninput = function() {
console.log(input.value);
};
</script>
If we want to handle every modification of an <input> then this event is the best choice.

I have been facing the same issue until I figured out how to do it. You can utilize a React hook, useEffect, to write a JS function that will trigger after React rendering.
useEffect(()=>{
document.title='fix onChange with onkeyup';
const box = document.getElementById('changeBox');
box.onkeyup = function () {
console.log(box.value);
}
},[]);
Note onchange is not fired when the value of an input is changed. It is only changed when the input’s value is changed and then the input is blurred. What you’ll need to do is capture the keypress event when fired in the given input and that's why we have used onkeyup menthod.
In the functional component where you have the <Input/> for the <form/>write this
<form onSubmit={handleLogin} method='POST'>
<input
aria-label= 'Enter Email Address'
type='text'
placeholder='Email Address'
className='text-sm text-gray-base w-full mr-3 py-5 px-4 h-2 border border-gray-primary rounded mb-2'
id='changeBox'
/>
</form>
Resulting Image :
Console Image

try onpropertychange.
it only works for IE.