When we are completing the question on leetcode or developing a complicated project, iteration is a useful syntax to traverse complex data structures.
The Array is a common data structure in computer science, the majority of languages provide while and for-loop to iterate the array. Moreover, High-level programming languages always provide some APIs to manipulate arrays.
JavaScript offers tons of methods to control, but querying methods were not provided until ES5. The APIs from ES5 decrease the codes and rapidly increase the readability.