JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.9/angular.min.js"></script>
<div data-ng-app="App">
    <div data-ng-controller="Ctrl">
        <p>Length is: {{string.length}}</p>
        <p>String is valid: {{valid}}</p>
        <input data-ng-model="string" />
    </div>
</div>

JavaScript

var app = angular.module('App',[]);

app.controller('Ctrl', function($scope){
    $scope.string = '';
    $scope.regex = /^(?=.*[0-9])(?=.*[a-zA-Z])([a-zA-Z0-9]{5,})$/; //any sequence of 5 or more alphanumeric characters that contains at least one letter, and at least one number, no white-space
    $scope.valid = false;
    
    $scope.$watch('string', function(){
        $scope.valid = $scope.regex.test($scope.string);
    })
});