Calculate total call duration In React Component using starttime and endtime props - reactjs

Question

I need to display the total time of call, the timelineData has already been getting from the props, I have tried to calculate the same using EndDate-StartDate but this logic does not seem to be correct.
import React from 'react'
import { Timeline, Typography, Col, Row } from 'antd'
import { connect } from 'react-redux'
const { Text } = Typography
export class DispositionTimeline extends React.Component {
render() {
return (
<Row className="dispopage">
<Col span={24}>
<Row>
<Col className="timeLineItem" span={24}>
<Row color="transparent">
<Col span={14}></Col>
<Col
style={{
paddingLeft: '8px',
fontWeight: '500'
}}
span={5}
>
Start Time
</Col>
<Col
style={{
paddingLeft: '8px',
fontWeight: '500'
}}
span={5}
>
End Time
</Col>
</Row>
<br />
<Timeline>
{this.props?.timeLineData?.map((value, index) => {
return (
<Timeline.Item>
<Col
className="timelineLabel"
span={14}
style={{
paddingRight: '16px'
}}
>
{value.name}
</Col>
<Col span={5}>
{/* {value.startTime} */}
{value.name !== 'End Call' && value.startTime}
</Col>
<Col span={5}>
{value.name === 'End Call' && value.startTime}
{value.endTime ? ` ${value.endTime}` : ''}
</Col>
</Timeline.Item>
)
})}
</Timeline>
</Col>
</Row>
<Row>
{this.props?.secondAgent?.anotherAgent === 'Primary Agent' ? (
<>
<Col className="timeLineEnd" span={18}>
<Text>Total Call Duration</Text>
</Col>
<Col className="timeLineEnd timeLineEndRight" span={6}>
<Text> {[...this.props?.timeLineData].pop()?.startTime}</Text>
</Col>
</>
) : (
''
)}
</Row>
</Col>
</Row>
)
}
}
export const mapStateToProps = (state, ownProps) => {
return {
timeLineData: ownProps?.timeLineData ? ownProps.timeLineData : state.timeLineData?.timeLineData,
totalDuration: state?.timeLineData?.payload,
secondAgent: state?.secondAgent?.secondAgent
}
}
export default connect(mapStateToProps, null)(DispositionTimeline)
The expression {[...this.props?.timeLineData].pop()?.startTime} is only displaying the startTime of Call. but I want to show the total time, I,e difference between end time and start time