Index in EJ2 JavaScript Form validator control

29 Aug 202324 minutes to read

The FormValidator can be used to validate the form elements before submitting to the server. That is, when typing wrong input values in the form element, it will show an alert message to notify the correction about the mistakes and it won’t allow to submit the form until the input gets correct value.

var options = {
    rules: {
        'user': { required: true },
        'age': { number: true, max: 25 }
    }
}
var formObject = new ej.inputs.FormValidator('#form-element', options);
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Form Validator</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/29.1.33/ej2-base/styles/material.css" rel="stylesheet">
    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/29.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <form id="form-element" class="form-horizontal">
            <div class="form-group">
                <label class="col-sm-3 control-label" for="user">User Name</label>
                <div class="col-sm-6">
                    <input type="text" id="required" name="user" class="form-control">
                </div>
            </div>
            <div class="form-group">
                <label class="col-sm-3 control-label" for="age">Age</label>
                <div class="col-sm-6">
                    <input type="text" id="number" name="age" class="form-control">
                </div>
            </div>
        </form>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>
#container {
    visibility: hidden;
    padding: 10px;
}

#loader {
    color: #008cff;
    height: 40px;
    width: 30%;
    position: absolute;
    top: 45%;
    left: 45%;
}

Validation Rules

Default Rules

The FormValidator has following default validation rules, which are used to validate the form.

Rules Description Example
required The form input element must have any input values a or 1 or -
email The form input element must have valid email format values <[email protected]>
url The form input element must have valid url format values http://syncfusion.com/
date The form input element must have valid date format values 05/15/2017
dateIso The form input element must have valid dateISO format values 2017-05-15
number The form input element must have valid number format values 1.0 or 1
digit The form input element must have valid digit values 1
maxLength Input value must have less than or equal to maxLength character length if maxLength: 5, check is valid and checking is invalid
minLength Input value must have greater than or equal to minLength character length if minLength: 5, testing is valid and test is invalid
rangeLength Input value must have value between rangeLength character length if rangeLength: [4,5], test is valid and key is invalid
range Input value must have value between range number if range: [4,5], 4 is valid and 6 is invalid
max Input value must have less than or equal to max number if max: 3, 3 is valid and 4 is invalid
min Input value must have greater than or equal to min number if min: 4, 5 is valid and 2 is invalid
regex Input value must have valid regex format if regex: '^[A-z]+$', a is valid and 1 is invalid

The rules option should map the input element’s name attribute.
The FormValidator library only validates the mapped input elements.

Defining Custom Rules

You can also define custom rules in the rules property and validate the form with custom logics.

The custom validation method need to return the boolean value for validating an input.

var customFn = (args) => {
    return args['value'].length >= 5;
};
var options = {
    rules: {
        'user': { required: true },
        'password': { minLength: [customFn, 'Need atleast 5 letters'] }
    }
};
var formObject = new ej.inputs.FormValidator('#form-element', options);
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Form Validator</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/29.1.33/ej2-base/styles/material.css" rel="stylesheet">
    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/29.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <form id="form-element" class="form-horizontal">
            <div class="form-group">
                <label class="col-sm-3 control-label" for="user">User Name</label>
                <div class="col-sm-6">
                    <input type="text" id="required" name="user" class="form-control">
                </div>
            </div>
            <div class="form-group">
                <label class="col-sm-3 control-label" for="password">Password</label>
                <div class="col-sm-6">
                    <input type="password" id="number" name="password" class="form-control">
                </div>
            </div>
        </form>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>
#container {
    visibility: hidden;
    padding: 10px;
}

#loader {
    color: #008cff;
    height: 40px;
    width: 30%;
    position: absolute;
    top: 45%;
    left: 45%;
}

Adding or Removing Rules

After creating FormValidator object, you can add more rules to an input element by using addRules
method and you can also remove an existing rule from the input element by using removeRules method.

import {FormValidator, FormValidatorModel} from '@syncfusion/ej2-inputs';

let options: FormValidatorModel = {
    rules: {
        'user': { required: true },
        'age': { number: true }
    }
}
let formObject: FormValidator = new FormValidator('#form-element', options);
// Add email rule to user element
formObject.addRules('user', { maxLength: 7 });
// Remove number rule from age element
formObject.removeRules('age', ['number']);

Validating a Form

You can manually trigger validation by calling the validate method of FormValidator.

var options = {
    rules: {
        'product_name': { required: true },
        'rating': { range: [1, 5] }
    }
};
var formObject = new ej.inputs.FormValidator('#form-element', options);
// validate all input elements in the form
formObject.validate();
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Form Validator</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/29.1.33/ej2-base/styles/material.css" rel="stylesheet">
    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/29.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <form id="form-element" class="form-horizontal">
            <div class="form-group">
                <label class="col-sm-3 control-label" for="product_name">Product Name</label>
                <div class="col-sm-6">
                    <input type="text" id="required" name="product_name" class="form-control">
                </div>
            </div>
            <div class="form-group">
                <label class="col-sm-3 control-label" for="rating">Rating</label>
                <div class="col-sm-6">
                    <input type="text" id="number" name="rating" class="form-control">
                </div>
            </div>
        </form>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>
#container {
    visibility: hidden;
    padding: 10px;
}

#loader {
    color: #008cff;
    height: 40px;
    width: 30%;
    position: absolute;
    top: 45%;
    left: 45%;
}

Validating a Single Element

The validate method have an optional argument, where you can pass an input element’s name attribute to validate its value against the defined rule.

import {FormValidator, FormValidatorModel} from '@syncfusion/ej2-inputs';

let options: FormValidatorModel = {
    rules: {
        'user': { required: true },
        'age': { number: true }
    }
}
let formObject: FormValidator = new FormValidator('#form-element', options);
// validate user element alone
formObject.validate('user');

Error Messages

The FormValidator provides default error messages for all default validation rules. It is tabulated as follows

Rules message
required This field is required.
email Please enter a valid email address.
url Please enter a valid URL.
date Please enter a valid date.
dateIso Please enter a valid date ( ISO ).
number Please enter a valid number.
digit Please enter only digits.
maxLength Please enter no more than {0} characters.
minLength Please enter at least {0} characters.
rangeLength Please enter a value between {0} and {1} characters long.
range Please enter a value between {0} and {1}.
max Please enter a value less than or equal to {0}.
min Please enter a value greater than or equal to {0}.
regex Please enter a correct value.

Customizing Error Messages

The default error message for a rule can be customizable by defining it along with concern rule object as follows.

var customFn = (args) => {
    return args['value'].length >= 5;
};
var options = {
    rules: {
        'user': { required: true },
        'password': { minLength: [customFn, 'Need atleast 5 letters'] }
    }
};
var formObject = new ej.inputs.FormValidator('#form-element', options);
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Form Validator</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/29.1.33/ej2-base/styles/material.css" rel="stylesheet">
    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/29.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <form id="form-element" class="form-horizontal">
            <div class="form-group">
                <label class="col-sm-3 control-label" for="user">User Name</label>
                <div class="col-sm-6">
                    <input type="text" id="required" name="user" class="form-control">
                </div>
            </div>
            <div class="form-group">
                <label class="col-sm-3 control-label" for="password">Password</label>
                <div class="col-sm-6">
                    <input type="password" id="number" name="password" class="form-control">
                </div>
            </div>
        </form>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>
#container {
    visibility: hidden;
    padding: 10px;
}

#loader {
    color: #008cff;
    height: 40px;
    width: 30%;
    position: absolute;
    top: 45%;
    left: 45%;
}

Customizing Error Placement

The FormValidator has an event customPlacement which can be used to place the error message from default position to desired custom location.

var options = {
    rules: {
        'user': { required: [true, 'User Name: required'] },
        'password': { minLength: [5, 'Password: need atleast 5 characters'] }
    },
    customPlacement: (inputElement, error) => {
        document.getElementById('error').appendChild(error);
    }
};
var formObject = new ej.inputs.FormValidator('#form-element', options);
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Form Validator</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/29.1.33/ej2-base/styles/material.css" rel="stylesheet">
    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/29.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <form id="form-element" class="form-horizontal">
            <div class="form-group">
                <label class="col-sm-3 control-label" for="user">User Name</label>
                <div class="col-sm-6">
                    <input type="text" id="required" name="user" class="form-control">
                </div>
            </div>
            <div class="form-group">
                <label class="col-sm-3 control-label" for="password">Password</label>
                <div class="col-sm-6">
                    <input type="password" id="number" name="password" class="form-control">
                </div>
            </div>
            <div class="form-group">
                <div class="col-sm-3 control-label"></div>
                <div class="col-sm-6">
                    <div id="error"></div>
                </div>
            </div>
        </form>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>
#container {
    visibility: hidden;
    padding: 10px;
}

#loader {
    color: #008cff;
    height: 40px;
    width: 30%;
    position: absolute;
    top: 45%;
    left: 45%;
}

#error {
    width: 100%;
    height: 70px;
    border: 1px solid red;
    padding: 10px;
}