To launch Developer Tools in Google chrome 1. Click on Customise and Control Google chrome button on the top right corner of the browser window 2. From the More tools option, select Developer tools Alternatively you can also use the keyboard shortcut F12. You can find JavaScript errors if any in the developer tools. Use the Console tab in the developer tools to find the source file of the JavaScript that caused the error. This will also tell you the line number of the error.