JSFiddle - React, Tailwind, and code Playground
HTML
<div ng-app="test" ng-controller="test">
<p>Select 1 prefilled with: {{selected1}}</p>
<select ng-model="selected1" ng-options="item for item in items"></select>
<p>Select 2 prefilled with: {{selected2}}</p>
<select ng-model="selected2" ng-options="item for item in items"></select>
<p>Select 3 prefilled with: {{selected3}}</p>
<select ng-model="selected3" ng-options="item for item in items">
<option value="" ng-if="!selected3">-- select field --</option>
</select>
<button ng-click="selected3 = undefined">Blank third option</button>
</div>
JavaScript
var app = angular.module('test', [])
.controller('test', function($scope) {
$scope.items = [1, 2,3,4,5];
$scope.selected1 = 1;
$scope.selected2 = 20;
$scope.selected3;
});