I am trying to get the text in a text box as the user types in it (jsfiddle playground):
function edValueKeyPress() {
var edValue = document.getElementById("edValue");
var s = edValue.value;
var lblValue = document.getElementById("lblValue");
lblValue.innerText = "The text box contains: " + s;
//var s = $("#edValue").val();
//$("#lblValue").text(s);
}
<input id="edValue" type="text" onKeyPress="edValueKeyPress()"><br>
<span id="lblValue">The text box contains: </span>
The code runs without errors, except that the value of the input text
box, during onKeyPress
is always the value before the change:
Question: How do I get the text of a text box during
onKeyPress
?
There are three events related to "the user is typing" in the HTML DOM:
onKeyDown
onKeyPress
onKeyUp
In Windows, the order of WM_Key
messages becomes important when the user holds down a key, and the key begins to repeat:
WM_KEYDOWN('a')
- user has pushed down the A keyWM_CHAR('a')
- an a
character has been received from the userWM_CHAR('a')
- an a
character has been received from the userWM_CHAR('a')
- an a
character has been received from the userWM_CHAR('a')
- an a
character has been received from the userWM_CHAR('a')
- an a
character has been received from the userWM_KEYUP('a')
- the user has released the A keyWill result in five characters appearing in a text control: aaaaa
The important point being that the you respond to the WM_CHAR
message, the one that repeats. Otherwise you miss events when a key is pressed.
In HTML things are slightly different:
onKeyDown
onKeyPress
onKeyDown
onKeyPress
onKeyDown
onKeyPress
onKeyDown
onKeyPress
onKeyDown
onKeyPress
onKeyUp
Html delivers an KeyDown
and KeyPress
every key repeat. And the KeyUp
event is only raised when the user releases the key.
Take aways
onKeyDown
or onKeyPress
, but both are still raised before the input.value
has been updatedonKeyUp
, because it doesn't happen as the text in the text-box changes.Question: How do I get the text of a text-box during onKeyPress
?
Answer: Use the value Property You can simply use the value property of the DOM input element to get the value of text input field. The following example will display the entered text in the input field on button click using JavaScript.
The onkeypress attribute fires when the user presses a key (on the keyboard).
A textbox is a common input control in HTML, but it has various hidden attributes. An HTML text box is an area on the screen wherein the user can enter the text input. It is a common input element found in many software programs, such as web browsers, email clients, and word processors.
Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes.
Keep it simple. Use both onKeyPress()
and onKeyUp()
:
<input id="edValue" type="text" onKeyPress="edValueKeyPress()" onKeyUp="edValueKeyPress()">
This takes care of getting the most updated string value (after key up) and also updates if the user holds down a key.
jsfiddle: http://jsfiddle.net/VDd6C/8/
Handling the input
event is a consistent solution: it is supported for textarea
and input
elements in all contemporary browsers and it fires exactly when you need it:
function edValueKeyPress() {
var edValue = document.getElementById("edValue");
var s = edValue.value;
var lblValue = document.getElementById("lblValue");
lblValue.innerText = "The text box contains: " + s;
}
<input id="edValue" type="text" onInput="edValueKeyPress()"><br>
<span id="lblValue">The text box contains: </span>
I'd rewrite this a bit, though:
function showCurrentValue(event)
{
const value = event.target.value;
document.getElementById("label").innerText = value;
}
<input type="text" onInput="showCurrentValue(event)"><br>
The text box contains: <span id="label"></span>
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