如何在控制器的ng-change中检测值null

Question

here's my view

md-input-container flex=""
        label Mynumber
        input type="number" ng-model="mynumber" ng-change="checkMynumber(mynumber)" step="0.01" ng-pattern="/^[0-9]+(\.[0-9]{1,2})?$/" string-to-number=""

my controller

$scope.checkMynumber = (number) =>
  if number?
    alert "true"
  else
    alert "false"

when i input my first number it alert True that was right but when i erase my inputed number it keeps alert True. i want to alert false when my input type is null.

Answer 1

 $scope.checkMynumber = function (number) {
   if(number) {
     alert(true)
   } else {
     alert(false)
   }
  }

Check this fiddle https://jsfiddle.net/aswathyb950/9jfww52h/

Answer 2

You can use

$scope.checkMynumber = function(number){ if (number!= null) alert "true" else alert "false" }

Answer 3

remove the ternary operator and stick with the if else conditions

 angular.module("app",[]) .controller("ctrl",function($scope){ $scope.checkMynumber = function(number) { if (number) alert("true") else alert ("false") } }) 

 <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script> <div ng-app="app" ng-controller="ctrl"> <input type="number" ng-model="mynumber" ng-change="checkMynumber(mynumber)" step="0.01" ng-pattern="/^[0-9]+(\\.[0-9]{1,2})?$/" string-to-number=""> </div> 

Answer 4

DEMO

 var myApp = angular.module('myApp',[]); myApp.controller('MyCtrl', ['$scope', function($scope) { $scope.checkMynumber = function(number) { number ? alert("true") : alert("false"); } }]); 

 <div ng-app="myApp" ng-controller="MyCtrl"> <input type="number" ng-model="mynumber" ng-change="checkMynumber(mynumber)" step="0.01" ng-pattern="/^[0-9]+(\\.[0-9]{1,2})?$/" string-to-number=""> </div> 

Answer 5

因为我的指令是字符串到数字，谢谢大家，它现在可以工作了

Answer 6

I don't understand why almost every answer here is in .js instead .coffee, like in question.. anyway you can imporove your code

1. ng-model="mynumber" ng-change="checkMynumber(mynumber)" I guess mynumber is your scope variable, so why you are passing this to method? (I don't have full code, but you are using fat arrow there, otherwise I would find reason to pass this as argument)

2. Your method checkMyNumber can be only like this:

   $scope.checkMynumber = => alert $scope.mynumber? + ""