如何在onKeyPress中获取输入文本框的文本？ [英] How to get text of an input text box during onKeyPress?
问题描述
我试图在用户输入文本框中获取文本（ 在输入文本框中获取值
保持简单。使用 onKeyPress（）和 onKeyUp（）：
<$ < p $ p>< code>< input id =edValuetype =textonKeyPress =edValueKeyPress（）onKeyUp =edValueKeyPress（）>
这样可以获取最新的字符串值（键输入后），并且可以更新用户按住一个键。
jsfiddle： http：// jsfiddle.net/VDd6C/8/
i am trying to get the text in a text box as the user types in it (jsfiddle playground):
<html>
<body>
<input id="edValue" type="text" onKeyPress="edValueKeyPress()"><br>
<span id="lblValue">The text box contains: </span>
</body>
<script>
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);
}
</script>
</html>
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?
Bonus Chatter
There are three events related to "the user is typing" in the HTML DOM:
onKeyDownonKeyPressonKeyUp
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')- anacharacter has been received from the userWM_CHAR('a')- anacharacter has been received from the userWM_CHAR('a')- anacharacter has been received from the userWM_CHAR('a')- anacharacter has been received from the userWM_CHAR('a')- anacharacter has been received from the userWM_KEYUP('a')- the user has released the A key
Will 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:
onKeyDownonKeyPressonKeyDownonKeyPressonKeyDownonKeyPressonKeyDownonKeyPressonKeyDownonKeyPressonKeyUp
Html delivers an KeyDown and KeyPress every key repeat. And the KeyUp event is only raised when the user releases the key.
Take aways
- i can respond to
onKeyDownoronKeyPress, but both are still raised before theinput.valuehas been updated - i cannot respond to
onKeyUp, 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?
Bonus Reading
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/
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