Deactivate "When the viewModel attribute holds the phrase 'some text'"

Question

Deactivate "When the viewModel attribute holds the phrase 'some text'"

I came across this answer on Stack Overflow regarding checking for a value in Knockout, but it seems to be outdated. I am attempting to achieve something like this:

<li>
   <span data-bind="text: Subject"></span>
   <!-- ko if: Subject.contains('Important') -->
      <i class="fa fa-exclamation-triangle"></i>
   <!-- /ko -->
</li>

In this scenario, I want the fontawesome icon to be displayed next to the Subject text if it contains the word 'Important'. Unfortunately, using 'contains' as a function does not work, and I am having trouble finding an updated solution.

javascript knockout.js

Answer 1

Answer №1

To incorporate a `contains` method for observables, you have the option to create it as a custom function by referring to Knockout's documentation. Another approach would be to add it exclusively to `vm.Subject`, or alternatively, inline it as recommended by Matt.

ko.observable.fn.contains = function (str) {
  return this().indexOf(str) > -1;
};

vm = {
  Subject: ko.observable('This is Important')
};

ko.applyBindings(vm);

setTimeout(() => vm.Subject('This is not'), 1500);

<link href="//maxcdn.bootstrapcdn.com/font-awesome/4.2.0/css/font-awesome.min.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<span data-bind="text: Subject"></span>
<!-- ko if: Subject.contains('Important') -->
<i class="fa fa-exclamation-triangle"></i>
<!-- /ko -->

Answer 2

To incorporate a `contains` method for observables, you have the option to create it as a custom function by referring to Knockout's documentation. Another approach would be to add it exclusively to `vm.Subject`, or alternatively, inline it as recommended by Matt.

ko.observable.fn.contains = function (str) {
  return this().indexOf(str) > -1;
};

vm = {
  Subject: ko.observable('This is Important')
};

ko.applyBindings(vm);

setTimeout(() => vm.Subject('This is not'), 1500);

<link href="//maxcdn.bootstrapcdn.com/font-awesome/4.2.0/css/font-awesome.min.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<span data-bind="text: Subject"></span>
<!-- ko if: Subject.contains('Important') -->
<i class="fa fa-exclamation-triangle"></i>
<!-- /ko -->

Answer 3

Answer №2

This is the final code snippet I used:

<li>
   <span data-bind="text: Subject"></span>
   <!-- ko if: Subject().indexOf('Important') !== -1 -->
   <i class="fa fa-exclamation-triangle"></i>
   <!-- /ko -->
</li>

It ended up working perfectly! Many thanks to Matt.kaaj for the assistance. Roy's method seems ideal for repeated instances, but in my case where I only needed to check once, the straightforward inline solution sufficed. Grateful for your help!

Answer 4

This is the final code snippet I used:

<li>
   <span data-bind="text: Subject"></span>
   <!-- ko if: Subject().indexOf('Important') !== -1 -->
   <i class="fa fa-exclamation-triangle"></i>
   <!-- /ko -->
</li>

It ended up working perfectly! Many thanks to Matt.kaaj for the assistance. Roy's method seems ideal for repeated instances, but in my case where I only needed to check once, the straightforward inline solution sufficed. Grateful for your help!

Deactivate "When the viewModel attribute holds the phrase 'some text'"

Answer №1

Answer №2

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