angular js input校验只能输入数字和字母 directive写法一则

js代码:.directive(‘validateNumberLetter‘, function () {  return {    require: ‘ngModel‘,    link:    function (scope, elm, attrs, ctrl) {      scope.$watch(attrs.ngModel, function(n){        if(!n) return;        var oldName = attrs.validateNumberLetter;        if(oldName !== n){          var reg=/[^A-Za-z0-9]/;          if (n.length) {            if(reg.test(n)){              // it is invalid, return undefined (no model update)              ctrl.$setValidity(‘validateNumberLetter‘, false);              return undefined;            }else{               // it is valid              ctrl.$setValidity(‘validateNumberLetter‘, true);              return n;            }          }        }      });    }  };})html代码:

<div class="form-group-right">  <input required validate-number-letter

    id="name"    name="name"    class="form-control verify-input"    type="text"    ng-model="volume.name"    ng-maxlength="255"    ng-disabled="context.mode === ‘extend‘ ||                 context.mode === ‘attach‘ ||                 context.mode === ‘detach‘"    placeholder="{% trans ‘enter a volume name‘ %}"/>  <p class="help-block alert-fixed alert-danger"    ng-show="form.name.$error.required && form.name.$dirty">    {% trans "A volume name is required." %}  </p>  <p class="help-block alert-fixed alert-danger"    ng-show="form.name.$error.maxlength && form.name.$dirty">    {% trans "Name length should be less than 255 chars." %}  </p>  <p class="help-block alert-fixed alert-danger"    ng-show="form.name.$error.validateNumberLetter && form.name.$dirty">    {% trans "should be letter" %}  </p></div>