JS checks if the element is contained in an array

Description

In the system need to check the correctness of the tax rate, must be a certain number of state-specified tax rates, of course, can be verified by if else, but you can also use to define an array and then verify whether it is included in the element for validation.

Pros: Add a tax rate without modifying the logic, just add it in the tax rate array.

Array.prototype.contains = function (obj) {var i = This.length;while (i--) {if (this[i] = = obj) {return true;}} return false;} var countryes=[' 3 ', ' 5 ', ' 6 ', ' One ', ' n ';    <span style= "White-space:pre" ></span>var ret=   countryes.contains (' 5 ')//return true        ret=   Countryes.contains (' + ')//return False

JS checks if the element is contained in an array