Salesforce Lightning Progress Bar With Conditional Theme

Lightning Component:

<aura:component>
    <!--declare handler for render the JS method for Progress bar-->
    <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>
    <!--declare attributes for progress bar value-->
    <aura:attribute name="progress" type="Integer" default="0"/>
    <div class="slds-m-around_xx-large">
        <div class="slds-progress-bar slds-progress-bar_large" aria-valuemin="0" aria-valuemax="100" aria-valuenow="{!v.progress}" role="progressbar">
            <span aura:id="prgBar" class="slds-progress-bar__value" style="{!'width:'+v.progress+'%'}">
                <span class="slds-assistive-text">Progress: {!v.progress}%</span>
            </span>
        </div>
    </div>
</aura:component>

Lightning JS Controller:

({
    //Specifying progress === 100 ? clearInterval(interval) : progress + 5 increases
    //the progress value by 5% and stops the animation when the progress reaches 100%
    //The progress bar is updated every 1000 milliseconds.
    doInit:  function (component, event, helper) {
        var interval = setInterval($A.getCallback(function () {
            var progress = component.get('v.progress');
            var prgBar = component.find("prgBar");
            if(progress >= 0){
                $A.util.addClass(prgBar,'slds-is-low');
            }
            if(progress >= 25){
                $A.util.removeClass(prgBar,'slds-is-low');
                $A.util.addClass(prgBar,'slds-is-medium');
            }
            if(progress >= 50){
                $A.util.removeClass(prgBar,'slds-is-medium');
                $A.util.addClass(prgBar,'slds-is-high');
            }
            if(progress >= 75){
                $A.util.removeClass(prgBar,'slds-is-high');
                $A.util.addClass(prgBar,'slds-is-critical');
            }
            component.set('v.progress', progress === 100 ? clearInterval(interval) : progress + 5);
        }), 1000);
    }
})

Lightning Style:

.THIS .slds-is-low {
    background-color: green!important;
}
.THIS .slds-is-medium{
    background-color: yellow!important;
}
.THIS .slds-is-high{
    background-color: orange!important;
}
.THIS .slds-is-critical{
    background-color: red!important;
}

Output:

Progress Indicator in Lightning Web Component

LWCProgressIndicator.html

<template>
    <div class="slds-theme_default">
        <div class="slds-p-around_medium">
            <lightning-progress-indicator type="path" current-step={selectedStep}>
                <lightning-progress-step label="Step1" onstepfocus={selectStep1} value="Step1">
                </lightning-progress-step>
                <lightning-progress-step label="Step2" onstepfocus={selectStep2} value="Step2">
                </lightning-progress-step>
                <lightning-progress-step label="Step3" onstepfocus={selectStep3} value="Step3">
                </lightning-progress-step>
                <lightning-progress-step label="Step4" onstepfocus={selectStep4} value="Step4">
                </lightning-progress-step>
            </lightning-progress-indicator>
            
            <div class="slds-m-vertical_medium">
                <lightning-button label="Back" class="slds-m-left_x-small" onclick={handlePrev}></lightning-button>
                <template if:false={isSelectStep4}>
                    <lightning-button variant="brand" class="slds-m-left_x-small" label="Next" onclick={handleNext}></lightning-button>
                </template>
                <template if:true={isSelectStep4}>
                    <lightning-button variant="brand" class="slds-m-left_x-small" label="Finish" onclick={handleFinish}></lightning-button>
                </template>
            </div>
        </div>
    </div>
</template>

LWCProgressIndicator.js

import { LightningElement, track } from 'lwc';

export default class LWCProgressIndicator extends LightningElement {
    @track selectedStep = 'Step1';

    handleNext() {
        var getselectedStep = this.selectedStep;
        if(getselectedStep === 'Step1'){
            this.selectedStep = 'Step2';
        }
        else if(getselectedStep === 'Step2'){
            this.selectedStep = 'Step3';
        }
        else if(getselectedStep === 'Step3'){
            this.selectedStep = 'Step4';
        }
    }

    handlePrev() {
        var getselectedStep = this.selectedStep;
        if(getselectedStep === 'Step2'){
            this.selectedStep = 'Step1';
        }
        else if(getselectedStep === 'Step3'){
            this.selectedStep = 'Step2';
        }
        else if(getselectedStep === 'Step4'){
            this.selectedStep = 'Step3';
        }
    }
     
    handleFinish() {
        alert('Finished...');
        this.selectedStep = 'Step1';
    }
     
    selectStep1() {
        this.selectedStep = 'Step1';
    }

    selectStep2() {
        this.selectedStep = 'Step2';
    }

    selectStep3() {
        this.selectedStep = 'Step3';
    }

    selectStep4() {
        this.selectedStep = 'Step4';
    }

    get isSelectStep4() {
        return this.selectedStep === "Step4";
    }
}

LWCProgressIndicator.js-meta.xml

<?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata" fqn="LWCProgressIndicator">
    <apiVersion>46.0</apiVersion>
    <isExposed>true</isExposed>
    <targets>
        <target>lightning__AppPage</target>
        <target>lightning__RecordPage</target>
        <target>lightning__HomePage</target>
    </targets>
</LightningComponentBundle>

Output:

Lightning Web Component Progress Bar

LWCProgressBar.html

<template>
    <div class="slds-theme_default">
        <div class="slds-p-around_medium">
            <lightning-progress-bar value={progress}></lightning-progress-bar>
        </div>
    </div>
</template>

LWCProgressBar.js

import { LightningElement, track } from 'lwc';

export default class LWCProgressBar extends LightningElement {
    @track progress = 0;

    connectedCallback() {
        this._interval = setInterval(() => {
            this.progress = this.progress === 100 ? 0 : this.progress + 1;
        }, 200);
    }
}

LWCProgressBar.js-meta.xml

<?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata" fqn="LWCProgressBar">
    <apiVersion>46.0</apiVersion>
    <isExposed>true</isExposed>
    <targets>
        <target>lightning__AppPage</target>
        <target>lightning__RecordPage</target>
        <target>lightning__HomePage</target>
    </targets>
</LightningComponentBundle>

Output:

OnLoad In Lightning Web Component

LWCDemo.html

<template>
    <div class="slds-text-heading_large slds-text-align_center">
        {greeting}
    </div>
</template>  

LWCDemo.js

import { LightningElement, track } from 'lwc';  
  
export default class LWCDemo extends LightningElement {  
  
    @track greeting;  
  
    connectedCallback() {
        this.greeting = 'Hello World!';
    }
}