javascript 淘汰赛 JS valueUpdate 按键不适用于启用绑定
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Knockout JS valueUpdate keypress not working for enable binding
提问by andy_coder
I have a 'Save' button on my form that has knockout enable binding. I added valueUpdate: 'keypress' to my knockout binding expression hoping for save button to become enabled on keypress. I have a simple input textbox with value knockout binding. Instead, page still requiring user to click away for save button to become enabled. HTML below. when user types in input, canSave becomes true enabling save button.
我的表单上有一个“保存”按钮，它具有淘汰启用绑定。我将 valueUpdate: 'keypress' 添加到我的淘汰赛绑定表达式中，希望在按键时启用保存按钮。我有一个带有值淘汰绑定的简单输入文本框。相反，页面仍然需要用户单击离开以启用保存按钮。下面的 HTML。当用户输入输入时， canSave 变为 true 启用保存按钮。
<button data-bind="click: save, enable: canSave, valueUpdate: 'keypress'">Save</button>
<h3><strong>First Name: <input data-bind="value: firstName"></strong></h3>
回答by Retsam
The valueUpdatebinding only makes sense coupled with a valuebinding; it should go on your input, not on your button.
的valueUpdate结合才有意义加上value结合; 它应该在您的输入上，而不是在您的按钮上。
<button data-bind="click: save, enable: canSave">Save</button>
<h3><strong>First Name: <input data-bind="value: firstName, valueUpdate: 'keypress'"></strong></h3>
Also, consider valueUpdate: 'input'if you're using browsers new enough to support it, or even the textInputbinding, if you're using KO >3.2
另外，valueUpdate: 'input'如果您使用的是 KO >3.2 ，请考虑您是否使用足够新的浏览器来支持它，甚至是textInputbinding
回答by thecodeparadox
Try this:
试试这个：
<button data-bind="click: save, enable: firstName().length > 0">Save</button>
<h3><strong>First Name: <input data-bind="value: firstName, valueUpdate:'keypress'"></strong></h3>
from you're code it seems, firstNameis an observable, if so then above code will do what you need. It will disable the button if there is not input else make it enable.
从你的代码看来，firstName是一个可观察的，如果是这样，那么上面的代码会做你需要的。如果没有输入，它将禁用该按钮，否则将其启用。
