JSFiddle - React, Tailwind, and code Playground

HTML

<script>
function Main($scope) {
    $scope.var = '5.0000';
}
</script>
<div ng-controller="Main">
    <input type="text" ng-model="var" ng-format="percent">
    <pre>var = {{var|json}}</pre>
</div>

JavaScript

angular.formatter('percent', {
  parse: function(value) {
    var m = value.match(/^(\d+)\/(\d+)/);
    if (m != null)
      return angular.filter.number(parseInt(m[1])/parseInt(m[2]), 2);
    return angular.filter.number(parseFloat(value)/100, 2);
  },
  format: function(value) {
    return angular.filter.number(parseFloat(value)*100, 0);
  },
});