ChromeFirefoxConsoleLogRetrieval.java

/* The code below is a snippet. It won't run or compile unless integrated in the appropriate class
** This is only supported on recent versions Firefox and Chrome when used with recent versions of 
** Firefox and Chrome driver.
*/

import org.openqa.selenium.logging.LogEntries;
import org.openqa.selenium.logging.LogEntry;
import org.openqa.selenium.logging.LogType;
import org.openqa.selenium.logging.LoggingPreferences;
import org.openqa.selenium.remote.CapabilityType;
import org.openqa.selenium.remote.DesiredCapabilities;

//Recommended while initializing the driver.
public void updateLoggingCaps(DesiredCapabilities desiredCaps) {
    LoggingPreferences logPrefs = new LoggingPreferences();
    logPrefs.enable(LogType.BROWSER, Level.ALL);
    desiredCaps.setCapability(CapabilityType.LOGGING_PREFS, logPrefs);
}

//I'd recommend doing this on test failures only. 
public void ExtractJSLogs(Webdriver driver) {
        LogEntries logEntries = driver.manage().logs().get(LogType.BROWSER);
        for (LogEntry entry : logEntries) {
            System.out.println(new Date(entry.getTimestamp()) + " " + entry.getLevel() + " " + entry.getMessage());
            //you can write it to a file 
        }
}