What is the difference between ng-if and data-ng-if directives ?

Last Updated : 23 Jul, 2019
The ng-if is a directive in AngularJS which is used to remove the HTML element if the value of the expression or variable is false, unlike ng-hide which just hides the HTML element from the DOM. Syntax: 
<element angular_directive=expression> Contents... </element>
There are few other options which behave like ng-if. There is no difference among them in functionality wise.
  • ng:if
  • ng_if
  • x-ng-if
  • data-ng-if
Note: The best practice is to use ng-if only. The reason behind why these options come into the picture is that in AngularJS we refer to the directive using camel case (example:ngIf) but when we use it in HTML since HTML is case insensitive we use a dash-delimited form (example:ng-if) or other delimiters as mentioned in the list above. So the AngularJS normalizes (It means it converts the delimiter form into camelcase.) the element's tag and figures out to which directive does the element belong. Example 1: This example uses "data-ng-if" directive. html 
<!DOCTYPE html>
<html>

<head>
    <title>
        What is the difference between ng-if
        and data-ng-if directives ?
    </title>
    
    <script src=
"https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js">
    </script>
</head>

<body ng-app="">
    <center>
        <h1 style="color:green">
            GeeksforGeeks
        </h1>

        <input ng-model="var1">

        <div data-ng-if="var1">
            <h3>
                This will disappear if the value of
                input var1 is set to false and will 
                appear again when true
            </h3>
        </div>
    </center>
</body>

</html>
Output: Example 2: This example uses "ng-if" directive. html 
<!DOCTYPE html>
<html>

<head>
    <title>
        What is the difference between ng-if
        and data-ng-if directives ?
    </title>
    
    <script src=
"https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js">
    </script>
</head>

<body ng-app="">
    <center>
        <h1 style="color:green">
            GeeksforGeeks
        </h1>

        <input ng-model="var1">

        <div ng-if="var1">
            <h3>
                This will disappear if the value of
                input var1 is set to false and will 
                appear again when true
            </h3>
        </div>
    </center>
</body>

</html>
Output:
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