The negation functionality in the visible binding of Knockout.js is not functioning properly

Question

The negation functionality in the visible binding of Knockout.js is not functioning properly

I'm having trouble using the visible data binding with a negation and it's not functioning as expected. I've come across various posts on stackoverflow suggesting that the NOT binding should be used as an expression. However, in my scenario, I'm only utilizing the length property, so I'm unsure how to incorporate an expression. Below is an example of what I have:

<div class="form-group" data-bind="visible:!users.length == 0">
<span>Some message here...</span
</div>

<div class="form-group" data-bind="visible:users.length > 0">
<span>User data grid here...</span
</div>

javascript knockout.js

Answer 1

Answer №1

I believe that the variable users is actually an observableArray, so the correct approach would be:

data-bind="visible: users().length !== 0"

To enhance clarity and efficiency, it would be beneficial to create a computed property within your view model and use that for binding instead:

showUsers = ko.computed(function(){

   return _this.users().length > 0;

});

Then, you can update your bindings as follows:

data-bind="visible: showUsers"

Or

data-bind="visible: !showUsers()"

For a complete example showcasing different techniques, refer to this JSFiddle link.

Answer 2

I believe that the variable users is actually an observableArray, so the correct approach would be:

data-bind="visible: users().length !== 0"

To enhance clarity and efficiency, it would be beneficial to create a computed property within your view model and use that for binding instead:

showUsers = ko.computed(function(){

   return _this.users().length > 0;

});

Then, you can update your bindings as follows:

data-bind="visible: showUsers"

Or

data-bind="visible: !showUsers()"

For a complete example showcasing different techniques, refer to this JSFiddle link.

The negation functionality in the visible binding of Knockout.js is not functioning properly

Answer №1

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