<input type="text" ng-model="searchText" />
<button ng-click="check(searchText)">Check!</button>
{{ searchText }}

$scope.check = function (searchText) {
 console.log(searchText);
}

“If you use ng-model, you have to have a dot in there.” 
Make your model point to an object.property and you'll be good to go.

<input ng-model="formData.searchText"/>
<button ng-click="check()">Check!</button>

$scope.formData = {};
$scope.check = function () {
 console.log($scope.formData.searchText.$modelValue);
}

<input type="password" pattern="[0-9]*" placeholder="请输入6位新密码" ng-model="password.new_password" ng-blur="validateLength()">

<input type="password" ng-model="password.new_password" ng-keyup="compare(password)" name="repassword" ng-pattern="/^[0-9]{1,6}$/" />