javascript - Using nativescript converters -

im trying hooks nativescript javascript , have basic question:

    let costformatter= {         toview(value){             console.log('got:' + value);             return '$' + value;         },         tomodel(value){             console.log('got:' + value);             return '$' + value;         }     };     http.getjson("<my api call>").then(function (r){         page.bindingcontext = {             deals: r,             costformatter:costformatter         };     }, function (e){         //// argument (e) error!         //console.log(e);     }); 

in above code, define cost formatter want $ added beside price on every sale price on listview labels. render list view im using:

<listview id="steamitems" items="{{ deals }}">                         <listview.itemtemplate>                             <gridlayout columns="*, *, 50, 50" rows="50, 50, auto, *">                                 <image src="{{ thumb }}" row="0" col="0" cssclass="thumb"/>                                 <label text="{{ title }}" key="1" row="0" col="1" cssclass="title"/>                                 <label text="{{ normalprice|costformatter }}" key="2" row="0" col="2" cssclass="normal-price"/>                                 <label text="{{ saleprice|costformatter }}" key="3" row="0" col="3" cssclass="sale-price"/>                              </gridlayout>                          </listview.itemtemplate>                     </listview> 

i not understand why

js: cannot find function or filter: costformatter 

for each row in listview in nativescript terminal. doing wrong?

it seems you're trying create so-called 'pipe'.

import { pipe, pipetransform } '@angular/core';  @pipe({   name: 'costformatter',   pure: true })  export class costformatterpipe implements pipetransform {   transform(price: string): string {     return "$ " + price;   } } 

then make sure add costformatterpipe declarations array of module want use in.