如何使用包含可观察到的字符串的表达式使基因敲除可见绑定起作用？

Question

Lets say there is an observable string stringVal defined in the view model.

data-bind="visible:!stringVal()" or any other expression containing stringVal() doesnt work. The error thrown is that a function stringVal() is expected in the view model.

Similar expression easily works with boolean observables.

Answer 1

Try this http://jsfiddle.net/w00t_/h6dy46s7/1/

HTML:

<h1 data-bind="visible: notstringval">
    <span data-bind="text: stringval()"></span>
    <span>yo</span>
</h1>

JS:

function myViewModel() {
    self = this;
    self.stringval = ko.observable("hello");
    self.notstringval = ko.pureComputed(function () {
        return !self.stringval();
    })
}

ko.applyBindings(myViewModel);

Answer 2

It's probably your version of Knockout. It works with versions 3.0+ but not with 2.x

 function myViewModel() { self = this; self.stringval = ko.observable("hello"); } ko.applyBindings(myViewModel); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.0.0/knockout-min.js"></script> <h1 data-bind="visible: !stringval()"> <span data-bind="text: stringval()"></span> <span>yo</span> </h1> <input data-bind="value: stringval" />