AngularJS Input Verification Principle Analysis

AngularJS input verification

AngularJS is a powerful front-end framework that allows developers to easily build complex single-page applications. It is very important to ensure the accuracy and completeness of the data when processing user input. AngularJS provides a built-in input verification mechanism that can help developers achieve this goal. This article will introduce the input verification capabilities of AngularJS in detail, including how it works, built-in validators, and how to customize them.

How AngularJS input verification works

AngularJS input verification is implemented through instructions. When the user enters data in the input field, AngularJS automatically checks whether the data complies with the specified verification rules. If the data does not comply with the rules, AngularJS marks the input field as invalid and displays the corresponding error message.

AngularJS built-in validator

AngularJS provides a range of built-in validators that can meet most basic verification needs. These built-in validators include:

• required: Make sure that the input field is not empty.
• ng-required: Determine whether the input field is required based on the value of the expression.
• minlength: Make sure that the length of the input field is at least the specified minimum value.
• maxlength: Make sure that the length of the input field does not exceed the specified maximum value.
• ng-minlengthandng-maxlength: Determine the minimum and maximum lengths of the input field based on the value of the expression.
• pattern: Make sure that the input field matches the specified regular expression.
• ng-pattern: Determine whether the input field needs to match the regular expression based on the value of the expression.
• email: Make sure the input field is a valid email address.
• number: Make sure the input field is a valid number.
• url: Make sure the input field is a valid URL.

How to use AngularJS input verification

To use AngularJS input validation, you need to add the corresponding verification directive to the HTML form element. For example, if you want to verify a required email address, you can write this:

<form name="myForm">
  <input type="email" name="email" ng-model="" required>
  <div ng-show=".$invalid && .$touched">
    Please enter a valid email address。
  </div>
</form>

In this example, we use the required directive to make sure the email address is required, and use type="email" to make sure the entered value is a valid email address. If the value entered by the user is invalid and the input field has been touched, AngularJS will display an error message.

How to customize AngularJS Verifier

While AngularJS provides a range of built-in validators, sometimes you may need to customize them based on specific business needs. To customize the validator, you can use the $validators object of the ngModel directive. For example, if you want to create a validator to ensure that the input field contains specific words, you could write this:

('myApp', [])
.directive('containsWord', function() {
  return {
    require: 'ngModel',
    link: function(scope, element, attrs, ngModel) {
      ngModel.$ = function(modelValue, viewValue) {
        var value = modelValue || viewValue;
        return value && () !== -1;
      };
    }
  };
});

In this example, we create a directive called containsWord, which accepts a parameter containsWord, indicating the word that needs to be included. We added a validator called containsWord using the $validators object of ngModel. If the input field contains the specified word, the validator returns true, otherwise false.

in conclusion

AngularJS input verification is a powerful feature that helps developers ensure that the data entered by users is accurate and complete. By using built-in validators and custom validators, developers can easily implement a variety of verification needs. Hope this article helps you better understand AngularJS input verification mechanism.

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