AngularJS conditional ng-disabled does not re-enable

问题

Given a conditionally disabled text input field using ng-disabled="truthy_scope_variable", AngularJS disables the field the first time the scope variable is falsified, but does not enable it on subsequent changes. As a result, the field remains disabled. I can only assume something went wrong, but the Console log is empty.

The truthy scope variable is tied to a radio button model and I can even $watch it change, but the input field's ng-disabled is not working as expected. I have manually tried calling $apply, but it looks like Angular is triggering DOM changes.

In controller:

$scope.new_account = true

Radio buttons:

<input type="radio" ng-model="new_account" name="register"
 id="radio_new_account" value="true" />

<input type="radio" ng-model="new_account" name="register"
 id="radio_existing_account" value="false" />

Conditionally disabled input field:

<input type="password" ng-disabled="new_account" id="login-password"
 name="password" ng-model="password" />

If I initially set $scope.new_account = false, the field is rendered disabled, but never re-enabled. Why is this happening?

回答1:

There is an alternative solution available just use

ng-value

 <input type="radio" ng-model="new_account" name="register"
 id="radio_new_account" ng-value="true" />

<input type="radio" ng-model="new_account" name="register"
 id="radio_existing_account" ng-value="false" />
      <input type="password" ng-disabled="new_account" id="login-password"
 name="password" ng-model="password" />

回答2:

That's because HTML attributes are always strings, so in your example ngDisabled is evaluating a string in both cases ("true" or "false").

To remedy, you should compare the model against the string value in ngDisabled:

ng-disabled="new_account == 'false'"

... or use a checkbox, to get the actual boolean value:

<input type="checkbox" ng-model="existing_account" name="register" id="checkbox_new_account" />
<label for="checkbox_new_account">Is Existing Account</label>

Password:
<input type="password" ng-disabled="existing_account" name="password" ng-model="password" />

Here's a PLNKR with both solutions.

回答3:

As of 2016 March the binded values will update the ui in Chrome and Firefox even when the ng-disabled is true but not in Safari. In Safari when you use ng-disabled the ui wont update although the input element value property will have the updated value (Check element.value after changing it.)

In Safari to force the ui updates with ng-model or ng-value directives you have to use ng-readonly instead of ng-disabled.

来源：https://stackoverflow.com/questions/17855304/angularjs-conditional-ng-disabled-does-not-re-enable