如何在按键事件之后获得 jQuery.val() ？

我有:

$(someTextInputField).keypress(function() {
alert($(this).val());
});

现在，警报总是返回 keypress之前的值(例如，字段为空，我键入‘ a’，警报就会给我)。然后我输入‘ b’，警报就会给我‘ a’... ...)。但是我想要 keypress之后的值-我怎么才能做到呢？

背景: 我希望在文本字段包含至少一个字符时立即启用一个按钮。所以我对每个 keypress事件运行这个测试，但是使用返回的 val()，结果总是落后一步。使用 change()事件对我来说不是一个选项，因为那样的话按钮将被禁用，直到您离开文本框。如果有更好的办法，我很高兴听到这个！

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小开

最佳答案

Change keypress to keyup:

$(someTextInputField).on("keyup", function() {
alert($(this).val());
});

keypress is fired when the key is pressed down, keyup is fired when the key is released.

小开

instead of keypress, use keyup.

小开

Try something like this:

$('#someField').keypress(function() {
setTimeout(function() {
if ($('#someField').val().length > 0)
$('#theButton').attr('disabled', false);
}, 1);
});

That simply introduces a timeout so that after the "keypress" event loop completes, your code will run almost immediately thereafter. Such a short timer interval (even if rounded up by the browser) will not be noticeable.

edit — or you could use "keyup" like everybody else says, though its semantics are different.

小开

Alternatively, you can use the keydown event with a timeout of 0.

That way, the changes will be applied instantly, instead of being applied when the user stops holding the key.

$(someTextInputField).on("keydown", function() {
setTimeout(function($elem){
alert($elem.val());
}, 0, $(this));
});

小开

Surprised that no one mentioned the js "input" event:

$(someTextInputField).on('input', function() {
alert($(this).val());
});