Vue Js Check Property Exist in Object: In  Vue.js, you can check if a property exists in an object using the hasOwnProperty method or the in operator.

The hasOwnProperty method checks whether the object has a property with the specified name and returns a boolean value. For example, obj.hasOwnProperty('property') will return true if the object obj has a property named property.

The in operator checks whether the specified property exists in the object or its prototype chain and returns a boolean value. For example, 'property' in obj will return true if the object obj has a property named property or if the property is present in its prototype chain.

Both methods are useful for checking if a property exists in an object and choosing the appropriate method depends on your specific use case.

How can you check if a property exists in an object using the hasOwnProperty method in Vue.js?

This is a simple  Vue.js app that uses two computed properties, hasName() and hasEmail(), to check if the user data object has a name and email property respectively.

The app then displays a message based on the computed property’s return value using the  Vue.js v-if directive. If the computed property returns true, the message “The user has an Name.” or “The user has an email address.” is displayed. If it returns false, the message “The user does not have an Name.” or “The user does not have an email address.” is displayed.

The data() function returns an object containing the userData object with a name property and an age property. However, there is no email property, which is why the “The user does not have an email address.” message is displayed.

Overall, this app demonstrates how to use  Vue.js computed properties and conditional rendering to display dynamic messages based on data conditions.

Vue Js Check property exist in Object Example

<div id="app">
    <p v-if="hasName">The user has an Name.</p>
    <p v-else>The user does not have an Name.</p>
    <p v-if="hasEmail">The user has an email address.</p>
    <p v-else>The user does not have an email address.</p>
</div>
<script type="module">
        const app = new Vue({
            el: "#app",

            data() {
                return {
                    userData: {
                        name: 'John',
                        age: 30
                    }
                };
            },
            computed: {
                hasName() {
                    return this.userData.hasOwnProperty('name');
                },
                hasEmail() {
                    return this.userData.hasOwnProperty('email');
                }
            }
        });
</script>

Output of Vue Js Check property exist in object

How can you check if a property exists in an object using the in operator in Vue.js?

This code uses the  Vue.js  framework to conditionally display a person’s age. If the ‘age’ property exists in the person object, then the age value will be displayed. Otherwise, a message indicating no age information is available will be displayed.

The  Vue instance is created with the el property set to “#app”, which specifies the element in the HTML where the  Vue app will be mounted. The data method returns an object with a person property that contains a name and occupation.

The v-if directive is used to conditionally render the age paragraph based on whether the ‘age’ property exists in the person object. The v-else directive is used to render the ‘No age information available.’ paragraph if the ‘age’ property doesn’t exist.

Overall, this code demonstrates how to use  Vue.js directives to conditionally render HTML elements based on data properties.

Vue Js Check Property Exist in Object using in operator Example

<div id="app">
     <p v-if="'age' in person">Age: {{ person.age }}</p>
     <p v-else>No age information available.</p>
</div>
<script type="module">
        const app = new Vue({
            el: "#app",

            data() {
                return {
                    person: {
                        name: 'John',
                        occupation: 'Developer'
                    }
                };
            },


        });
</script>

Output of above example