1. When the content entered in the input box is not standardized and the form is submitted, the input input box will prompt an error, and the outer p border of the input will turn red. When I re-enter the input box, the first Starting from the first input character, the color of the outer p border changes to the normal color.

The following is the code

<form action="" class="signup_form" method="post" name="checkForm" ng-init="isEmpty=false;">
    <p class="form_item  form_item_account">
        <label for=""> 用&nbsp;&nbsp;户&nbsp;&nbsp;名 </label>
        <input type="text" class="form_account" placeholder="您的账户名和登录名"
                id="form_item_account"
                ng-model="account"
                name="account"
                required
                ng-pattern="regularList.account"
                ng-class="{'warnning':checkForm.account.$focused,'error':(!isEmpty && checkForm.account.$blured &&
                 checkForm.account.$error.pattern) || (isEmpty && checkForm.account.$invalid)}"
                ng-blur="checkForm.account.$blured = true;checkForm.account.$focused = false;"
                ng-focus="checkForm.account.$focused = true;checkForm.account.$blured = false;accountValid()"
                autocomplete="off"
                >
        <i></i>
    </p>
    <p class="form_item">
        <button class="btn_register" id="btn_register" ng-click="isEmpty=true; confirm()">立即注册</button>
        <i></i>
    </p>
</form>

Add the form_item_error class in js, and the outer p border of the input box turns red. Remove this class, and the outer p border becomes normal

function checkError(form){
    var item = form.parent();
    if(form.hasClass("error")){
        item.addClass("form_item_error");
    }else if(item.hasClass("form_item_error")){
            item.removeClass("form_item_error");

    }else{
        item.removeClass("form_item_error");
    }
}
$scope.confirm = function () {
            $scope.accountValid = function(){
                checkError(form_account);
            }
 }

Effect
Error

In case of error, enter the content and the border will return to normal

Please give me some advice, thank you