If your nonimmigrant status expires while your extension is pending and you are extending an E-1, E-2, E-3, H-1B, H-1B1, H-2A, H-2B, H-3, L-1, O-1, P-1, R-1, or TN visa, you will still be allowed to remain in the United States and to continue your employment for up to 240 days. However, if your application for an extension is denied, your authorization to work is immediately revoked.
You may travel abroad after filing an application for extension and still maintain your lawful status but you must either return to the United States before your current nonimmigrant visa expires or remain abroad until your extension is approved and you have obtained a new visa, if your current visa has expired.