javascript - KnockoutJS : Create binding handler to change value to enum -

i have knockout custom binding takes value , returns enum. user readability. problem when passing in parameter binding, comes blank. i've tried passing in parameter observable, ex: purchaseorderstatus[status()].

the view:

 <td style="vertical-align: top">             <label>status</label><br />             <span data-bind="text: purchaseorderstatus[status]"></span>         </td> 

the javascript :

purchaseorderstatus = function() { }; purchaseorderstatus.prototype = { closed: 67,  deleted: 68,  finalized: 70,  open: 79} purchaseorderstatus.registerenum('purchaseorderstatus', false); 

the way should work if value 70, user sees finalized.

how this.

function model() {    var self = this;    this.purchaseorderstatus = ko.observable({      '67': 'closed',      '68': 'deleted',      '70': 'finalized',      '79': 'open'    });    this.status = ko.observable('68');  }    var mymodel = new model();    $(document).ready(function() {    ko.applybindings(mymodel);  });

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.2/knockout-min.js"></script>  <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>    <span data-bind="text: purchaseorderstatus()[status()]"></span>