JavaScript 数组是 NaN?AngularJS ngModel [英] JavaScript array is NaN? AngularJS ngModel

问题描述

我想看看 ngModel 的价值是什么:

I'm trying to see what the value of an ngModel is:

.directive('myDir', function() {
  return {
    require: '?ngModel',
    link: function(scope, elm, attr, ngModel) {
      if (!ngModel)
        return

      console.log(ngModel)
      console.log(ngModel.$modelValue)
    }
  };
})

即使我的 ngModel 是一个数组，它也会记录 NaN?

Even though my ngModel is an array it logs NaN?

推荐答案

$viewValue 和 $modelValue默认为 Number.NaN -- Not - a - Number 的 JavaScript 定义.

$viewValue and $modelValue default to Number.NaN -- JavaScript Definition for Not - a - Number.

检查 Github 然后你会发现

check Github and you find that

var NgModelController = ['$scope', '$exceptionHandler', '$attrs', 
                                 '$element', '$parse',
'$animate', '$timeout',
    function($scope, $exceptionHandler, $attr, $element, $parse, 
                   $animate, $timeout) 
  {
  this.$viewValue = Number.NaN;
  this.$modelValue = Number.NaN;

为什么这样方便?因为 AngularJS 试图避免出现像 null 和 undefined 这样的情况.视图值和模型值由范围"绑定和定义.这就是 $scope 服务的重点——管理 modelValue 和 viewValue.

Why is this convienient? Because AngularJS tries to avoid having cases like null and undefined. View Values and Model Values are bound and defined by "scope". That's the point of the $scope service -- to manage the modelValue and viewValue.

在 AngularJS 服务访问它们之前，它们默认为 number.NaN

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