JSFiddle - React, Tailwind, and code Playground

HTML

<div ng-app='converterApp' ng-controller='converterCtrl'>Meters
    <input type="text" ng-model="m" ng-change="km = m/1000" />
    <br>Kilometers
    <input type="text" ng-model="km" ng-change="m = km*1000" />
</div>

JavaScript

'use strict';

angular.module('converterApp', [])
  .controller('converterCtrl', function ($scope) {
    $scope.m = 7000;
    $scope.km = $scope.m / 1000;
});