How to add custom style css and change the text color & text size through JavaScript in lightning web component

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Hey guys, today in this post we are going to learn about How to add custom style css and change the text color & text size through JavaScript in lightning web component – LWC.

Files we used in this post example

lwcApplyCss.html	Lightning Web Component HTML	Template HTML file for used to write HTML element for user interface.
lwcApplyCss.js	Lightning Web Component JavaScript	It is holding onclick functionality for add custom style CSS to change the text color and text size.
lwcApplyCss.js-meta.xml	XML Meta File	It is used for where this lightning web component you want to exposed.
lwcApp.app	Lightning Application File	It is used for call the component and preview on browser..

Live Demo

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

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

lwcApplyCss.html [Lightning Web Component HTML]

  <template>
    <lightning-card title="Apply  Custom Style CSS in LWc through Javascript" custom-icon="custom:icon15">
        <div class="containerOver slds-p-around--medium slds-m-horizontal--medium" >
            <h1>Easy to learn Step-by-Step online tutorial from www.w3web.net</h1>
            <p class="listItem">Hi welcome to online tutorial www.w3web.net</p>
            <p class="listItem">w3web.net is the place where you can learn step-by-step about Blog, WordPress, Salesforce Lightning Component, Lightning Web Component (LWC), Visualforce, Technical of Computer Application, Salesforce Plugin, JavaScript, Jquery, CSS, Computer & Accessories, Software Configuration, Customization, Development and much more…</p></br></br>
            <div class="slds-text-align--center"><lightning-button label="Change Styling CSS" class="cssStyleBtn" variant="brand" onclick={customStyleChange}></lightning-button></div>
            </div>
    </lightning-card>
</template>

<lightning-card title="Apply Custom Style CSS in LWc through Javascript" custom-icon="custom:icon15">

<h1>Easy to learn Step-by-Step online tutorial from www.w3web.net</h1>

<p class="listItem">Hi welcome to online tutorial www.w3web.net</p>

<p class="listItem">w3web.net is the place where you can learn step-by-step about Blog, WordPress, Salesforce Lightning Component, Lightning Web Component (LWC), Visualforce, Technical of Computer Application, Salesforce Plugin, JavaScript, Jquery, CSS, Computer & Accessories, Software Configuration, Customization, Development and much more…</p></br></br>

</div>

</lightning-card>

</template>

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

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

lwcApplyCss.js [LWC JavaScript File]

  import { LightningElement } from 'lwc';

export default class LwcApplyCss extends LightningElement {

    renderedCallback(){
		this.template.querySelector("h1").style.color="blue";
        this.template.querySelector("h1").style.textAlign="center";
        this.template.querySelector("h1").style.fontSize="16px";
        this.template.querySelector(".containerOver").style.boxShadow="0px 0px 5px #0007ea";
                this.template.querySelectorAll(".listItem").forEach(item=>{
                Object.assign(item.style, {color:'green',textAlign:'center',fontSize:'15px'});
        }); 
   }    


   customStyleChange(event){ 
    this.template.querySelector("h1").style.fontSize="22px";
    this.template.querySelector("h1").innerHTML="Easy to learn LWC tutorial from w3web.net";    
    this.template.querySelector(".containerOver").style.boxShadow="0px 0px 5px #ff0000"; 
      this.template.querySelectorAll(".listItem").forEach(item=>{
            Object.assign(item.style, {color:'red',textAlign:'center',fontSize:'18px'});
     });
   }
 

}

import { LightningElement } from 'lwc';

export default class LwcApplyCss extends LightningElement {

renderedCallback(){

this.template.querySelector("h1").style.color="blue";

this.template.querySelector("h1").style.textAlign="center";

this.template.querySelector("h1").style.fontSize="16px";

this.template.querySelector(".containerOver").style.boxShadow="0px 0px 5px #0007ea";

this.template.querySelectorAll(".listItem").forEach(item=>{

Object.assign(item.style, {color:'green',textAlign:'center',fontSize:'15px'});

});

}

customStyleChange(event){

this.template.querySelector("h1").style.fontSize="22px";

this.template.querySelector("h1").innerHTML="Easy to learn LWC tutorial from w3web.net";

this.template.querySelector(".containerOver").style.boxShadow="0px 0px 5px #ff0000";

this.template.querySelectorAll(".listItem").forEach(item=>{

Object.assign(item.style, {color:'red',textAlign:'center',fontSize:'18px'});

});

}

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

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

lwcApplyCss.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 Lightning Application

Step 4:- Create Lightning Application : lwcApp.app

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

lwcApp.app [Component Application File]

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

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

<c:lwcApplyCss/>

</aura:application>

Further post that would you like to learn in LWC

8 thoughts on “How to add custom style css and change the text color & text size through JavaScript in lightning web component – LWC”

Nawaz Rizvi

December 21, 2020 at 5:02 pm

Thanks for this custom style css blog. I am happy to read this blog. I was helpful for me for boosting my knowledge.
Online WebTech

December 25, 2020 at 4:29 am

Thanks for the best knowledge of custom style of CSS. Does good hosting matters on our websites.
DudeTechPro

December 25, 2020 at 4:44 am

Thanks for the technical information regarding CSS. I want to get more infortaion.
Ravi Mishra

December 26, 2020 at 6:23 am

I like your blog
Ravi Mishra

December 26, 2020 at 6:24 am

I like your blog
Praveen Patil

January 8, 2021 at 1:57 pm

Excellent blog. Found very useful.
Masud Ali

April 6, 2021 at 5:03 pm

Excellent blog with huge information..Thank you
Noor Wali Baz

April 10, 2021 at 10:14 pm

it is a very good blog about css and font size. also explain a free plugin for wordpress user to change the font in wp.