The style of all ordinances of a city of the second class or village shall be: Be it ordained by the mayor and city council of the city of ……, or the chairperson and board of trustees of the village of ……. . All ordinances of a general nature shall, before they take effect, be published, within fifteen days after they are passed, (1) in a legal newspaper in or of general circulation in such city or village or (2) by publishing the same in book, pamphlet, or electronic form. In case of riot, infectious or contagious diseases, or other impending danger, failure of public utility, or any other emergency requiring its immediate operation, such ordinance shall take effect upon the proclamation of the mayor or chairperson of the village board of trustees, posted in at least three of the most public places in the city or village. Such emergency ordinance shall recite the emergency, be passed by a three-fourths vote of the city council or village board of trustees, and be entered of record on the minutes of the city or village. The passage, approval, and publication of all ordinances shall be sufficiently proved by a certificate under seal of the city or village from the city clerk or village clerk, showing that such ordinance was passed and approved and when and in what legal newspaper the ordinance was published. When ordinances are printed in book, pamphlet, or electronic form, purporting to be published by authority of the village board of trustees or city council, the ordinance need not be otherwise published, and such book, pamphlet, or electronic form shall be received as evidence of the passage and legal publication of such ordinances as of the dates mentioned in such book, pamphlet, or electronic form in all courts without further proof.