Not all emergency loans need to be paid back in 30 days, however the longer the term of the emergency loan the higher the interest rate will be. Reputable financial institutes will say within the usury or loaning requirements of the state, but other businesses, including some online only companies, may not.
When you are providing online information for an emergency account be sure you are actually giving information to the company you think you are. Never follow links or pop ups as these may be phishing sites, designed to look like reputable banks or lenders.