A small example of custom event & dispatch event where we define a custom event in child component and passing values from child component to parent component in -- LWC

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Hey guys, today in this post we are going to learn about How to define a custom event in child lightning web component and passing values from child component to parent component in — LWC

Files we used in this post example:-

lwcParent.html	Lightning Web Component HTML	Template HTML file for used to write HTML element for user interface.
lwcParent.js	Lightning Web Component JavaScript	It is holding child component and it’s value.
lwcParent.js-meta.xml	XML Meta File	It is used for where this lightning web component you want to exposed.
lwcChild.html	Lightning Web Component HTML	It is child HTML file and calling on lwcParent.html.
lwcChild.js	Lightning Web Component JavaScript	It is holding @api public property with handler change functionality and it’s calling into parent componet.
lwcChild.js-meta.xml	XML Meta File	It is used for where this lightning web component should be exposed.
eventApplwc.app	Lightning Application	It is used for call the parent component to preview on browser.

Live Demo

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Start lwcParent Component

Step 1:- Create Lightning Web Component : lwcParent.html

SFDX:Lightning Web Component >> New >> lwcParent.html

lwcParent.html [Lightning Web Component HTML]

  <template>
    <lightning-card title="How to pass value from child to parent component in lwc" icon-name="custom:custom11">
   
        <div class="slds-wrap slds-grid">
            <div class="slds-col slds-size_12-of-12 slds-p-horizontal--small slds-m-bottom--medium">
            
                <h3><b>lwcChild Component</b></h3>
                <c-lwc-child ondemoevent={handleChange}></c-lwc-child>

                 <h3><b>lwcParent Component</b></h3>
                 <b style="color:brown; margin-top:15px;">The Name Value Is:-</b> {currentVal}
            </div>
        </div>
 
</lightning-card>
</template>

<lightning-card title="How to pass value from child to parent component in lwc" icon-name="custom:custom11">

<h3><b>lwcChild Component</b></h3>

<c-lwc-child ondemoevent={handleChange}></c-lwc-child>

<h3><b>lwcParent Component</b></h3>

<b style="color:brown; margin-top:15px;">The Name Value Is:-</b> {currentVal}

</div>

</lightning-card>

</template>

Step 2:- Create Lightning Web Component : lwcParent.js

SFDX:Lightning Web Component >> New >> lwcParent.js

lwcParent.js [LWC JavaScript File]

import {LightningElement,api} from 'lwc';
export default class LwcParent extends LightningElement {
       @api currentVal;
       handleChange(event){
        this.currentVal=event.detail;
        //window.console.log('fldInp# ' + this.nameInp);        
        }
}

import {LightningElement,api} from 'lwc';

export default class LwcParent extends LightningElement {

@api currentVal;

handleChange(event){

this.currentVal=event.detail;

//window.console.log('fldInp# ' + this.nameInp);

}

Step 3:- Create Lightning Web Component : lwcParent.js-meta.xml

SFDX:Lightning Web Component >> New >> lwcParent.js-meta.xml

lwcParent.js-meta.xml [LWC Meta Data XML]

   <?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata">
    <apiVersion>45.0</apiVersion>
    <isExposed>true</isExposed>
    <targets>
        <target>lightning__AppPage</target>
        <target>lightning__RecordPage</target>
        <target>lightning__HomePage</target>
        <target>lightning__Tab</target>
      </targets>
</LightningComponentBundle>

<?xml version="1.0" encoding="UTF-8"?>

<target>lightning__AppPage</target>

<target>lightning__RecordPage</target>

<target>lightning__HomePage</target>

<target>lightning__Tab</target>

</targets>

</LightningComponentBundle>

Start lwcChild Component

Step 4:- Create Lightning Web Component : lwcChild.html

SFDX:Lightning Web Component >> New >> lwcChild.html

lwcChild.html [Lightning Web Component HTML]

   <template> 
    <div class="slds-wrap slds-grid">
        <div class="slds-col slds-size_12-of-12 slds-p-horizontal--small slds-m-bottom--medium">
            <lightning-input type="text" label="Name" name="name" onchange={handleChangeName}></lightning-input>
        </div>
    </div>
</template>

<lightning-input type="text" label="Name" name="name" onchange={handleChangeName}></lightning-input>

</div>

</template>

Step 5:- Create Lightning Web Component : lwcChild.js

SFDX:Lightning Web Component >> New >> lwcChild.js

lwcChild.js [LWC JavaScript File]

  import { LightningElement,api } from 'lwc';

export default class LwcChild extends LightningElement {  
   @api nameInp;
   handleChangeName(event){ 
     this.nameInp = event.target.value;
     const myDemoEvent = new CustomEvent('demoevent',{
         detail:this.nameInp
        });
     this.dispatchEvent(myDemoEvent);
     //window.console.log('nameInpBBB' + this.nameInp);
   }

}

import { LightningElement,api } from 'lwc';

export default class LwcChild extends LightningElement {

@api nameInp;

handleChangeName(event){

this.nameInp = event.target.value;

const myDemoEvent = new CustomEvent('demoevent',{

detail:this.nameInp

});

this.dispatchEvent(myDemoEvent);

//window.console.log('nameInpBBB' + this.nameInp);

}

Step 6:- Create Lightning Web Component : lwcChild.js-meta.xml

SFDX:Lightning Web Component >> New >> lwcChild.js-meta.xml

lwcChild.js-meta.xml [LWC Meta Data XML]

  <?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata">
    <apiVersion>45.0</apiVersion>
    <isExposed>true</isExposed>
</LightningComponentBundle>

<?xml version="1.0" encoding="UTF-8"?>

</LightningComponentBundle>

Start Application Component

Step 7:- Create Lightning Application : eventApplwc.app

From Developer Console >> File >> New >> Lightning Application

eventApplwc.app [Component Application File]

   <aura:application extends="force:slds">
   <c:lwcParent/>
</aura:application>

<aura:application extends="force:slds">

<c:lwcParent/>

</aura:application>

Further post that would you like to learn in LWC

5 thoughts on “A small example of custom event & dispatch event where we define a custom event in child component and passing values from child component to parent component in — LWC”

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December 7, 2020 at 4:48 am

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December 8, 2020 at 12:59 pm

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Shahriar

December 8, 2020 at 3:58 pm

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idsbuddy

December 19, 2020 at 9:57 am

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Joganiwellness

February 4, 2021 at 9:10 am

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A small example of custom event & dispatch event where we define a custom event in child component and passing values from child component to parent component in — LWC

Files we used in this post example:-

Start lwcParent Component

lwcParent.html [Lightning Web Component HTML]

lwcParent.js [LWC JavaScript File]

lwcParent.js-meta.xml [LWC Meta Data XML]

Start lwcChild Component

lwcChild.html [Lightning Web Component HTML]

lwcChild.js [LWC JavaScript File]

lwcChild.js-meta.xml [LWC Meta Data XML]

Start Application Component

eventApplwc.app [Component Application File]

Related Topics

5 thoughts on “A small example of custom event & dispatch event where we define a custom event in child component and passing values from child component to parent component in — LWC”

Leave a Comment Cancel reply

Files we used in this post example:-

Start lwcParent Component

lwcParent.html [Lightning Web Component HTML]

lwcParent.js [LWC JavaScript File]

lwcParent.js-meta.xml [LWC Meta Data XML]

Start lwcChild Component

lwcChild.html [Lightning Web Component HTML]

lwcChild.js [LWC JavaScript File]

lwcChild.js-meta.xml [LWC Meta Data XML]

Start Application Component

eventApplwc.app [Component Application File]

Related Topics

5 thoughts on “A small example of custom event & dispatch event where we define a custom event in child component and passing values from child component to parent component in — LWC”

Leave a Comment Cancel reply

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