# INDEXOF Returns the index of the first occurrence of an input number in an array of numbers. Node references are also accepted as arguments. The function returns 0 if the value is not found in the input array. ## Syntax ```javascript indexof(list, value) ``` ## Arguments list - The input array of numbers to be checked. value - The number to be searched for in the list. ## Example ```javascript INDEXOF([2,4,6,8,10],8) ``` Returns 4. ``` INDEXOF([2,4,6,8,10],2) ``` Returns 1. In the example below, the Indexof function is used to check whether the Revenue in any quarter is equal to the Sales for Q1.