React

import React, { Component } from 'react';
import { Chip, CircularProgress } from 'material-ui';

export default class LogView extends Component {
    style = {
        position: "relative";
    }

    chipStyle = {
        fontWeight: "600",
        fontSize: "12px",
        display: "inline-block",
    }

    render() {
        let loadingStyle = {
            margin: "auto",
            textAlign: "center"
        };

        if (!this.props.isLoading) {
            loadingStyle.display = "none";
        }

        return (
            <div style={this.style}>
                {this.props.logs.map((value, key) =>
                    <div key={key} className="line">
                        <Chip style={this.ChipStyle}>{value.timestamp}</Chip> {value.message}
                    </div>
                )}
                <CircularProgress size={80} thickness={5} style={loadingStyle} />
            </div>
        );
    }
}