淘汰赛js不从视图模型更新

Question

So I have a the following textarea in my view that I am attempting to update via a knockout binding.

Here is the code from the View:

<textarea disabled id="CCHPISentence" style="width:99.7%; height:75px; resize: none; font-family:Verdana; overflow: auto;" data-bind="text: fullSymptomTextObservable"> </textarea>

Here is the Jquery function that applies the bindings, I am wondering if my issue is here:

   $(function () {
    ko.applyBindings(symptomTextViewModel, document.getElementById("CCHPISentence"))
})

Here is my ViewModel:

function symptomTextViewModel(fullText) {
if (fullText === undefined)
{ fullText = ""}
this.fullSymptomTextObservable = ko.observable(fullText.toString())

}

Here is a snip from the js function that calls my ViewModel. I am building the fullText variable in this 2nd js function:

    //FINAL PARAGRAPH KNOCKOUT VM MAPPING
fullText = sentence1 + sentence2 + sentence3 + sentence4 + sentence5
var symptSentViewModel = new symptomTextViewModel(fullText)
symptomTextViewModel(fullText);

Thanks so much to anybody in advance who can assist me here. I feel like I am missing something stupid, I have tried this every different way that I can think of with no luck.

Answer 1

it would be easier to make fullSymptomTextObservable a pureComputed observable. That way as the various sentences change so will the full sentence. This way you are taking advantage of knockoutjs.

 function SymptomTextViewModel(fullText) { var self = this; if (fullText === undefined) { fullText = "" } self.fullSymptomTextObservable = ko.observable(fullText.toString()) } var vm = new SymptomTextViewModel('This is a test paragraph. Watch for the alert();'); ko.applyBindings(vm,document.getElementById("CCHPISentence")); alert("about to use the vm variable to access the text."); vm.fullSymptomTextObservable('Changing it to something else'); alert("about to use the ko.dataFor function"); var testVm = ko.dataFor(document.getElementById("CCHPISentence")); testVm.fullSymptomTextObservable("Maybe this would be better suited to what you need."); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script> <textarea disabled id="CCHPISentence" style="width:99.7%; height:75px; resize: none; font-family:Verdana; overflow: auto;" data-bind="text: fullSymptomTextObservable"></textarea> 

Answer 2

First of all I would fix all missing semicolons in your code. Than check if scope of 'this' in your view models function is correct. Some info from browser console would be also helpful. Check if there isn't any errors which knockout would throw.