let's colorize react-native log-ios / log-android

log_device.js

const spawn = require('child_process').spawn;
const chalk = require('chalk');
const endOfLine = require('os').EOL;

const deviceType = process.argv[2];
const cmd = spawn('react-native', [deviceType == 'ios' ? 'log-ios' : 'log-android']);

function log(msg) {
    console.log(msg);
}

cmd.stdout.on('data', function(data) {
    msgs = data.toString();

    msgs.split(endOfLine).forEach(function(msg) {
        if (msg.length <= 0) return;

        const pos = msg.indexOf(':', msg.indexOf('React'));
        const header = msg.substr(0, pos + 1);
        const headerData = header.split(/\s+/);
        const level = headerData[4];

        const bodyStr = msg.substr(pos + 1);
        const headerStr = headerData.join(' ');

        switch (level) {
            case 'V': // Verbose (lowest priority)
                log(chalk.green(headerStr) + bodyStr);
                break;
            case 'D': // Debug
                log(chalk.gray(headerStr + bodyStr));
                break;
            case 'I': // Info (default priority)
                log(chalk.blue(headerStr) + bodyStr);
                break;
            case 'W': // Warning
                log(chalk.yellow(headerStr + bodyStr));
                break;
            case 'E': // Error
                log(chalk.red(headerStr + bodyStr));
                break;
            case 'F': // Fatal
                log(chalk.red.bold(headerStr + bodyStr));
                break;
            case 'S': // Silent
                log(chalk.gray(headerStr) + bodyStr);
                break;
            default:
                log(chalk.gray(headerStr) + bodyStr);
        }
    });
});

cmd.stderr.on('data', function(data) {
    console.log('stderr: ' + data.toString());
});

cmd.on('exit', function(code) {
    console.log('child process exited with code ' + code.toString());
});