Please explain usage of _.identity(value) of underscore.js

Question

Please explain usage of _.identity(value) of underscore.js. Not able to understand it from the documentation ( http://underscorejs.org/#identity ).

Can

Answer 1

It's essentially a no-operation function. It returns the value of whatever was passed into it.

The part about it being used as a "default iterator" within the library itself means that in other functions which may have an optional "iterator" parameter (which is likely used as a function to apply to each element of an array of some kind), if no iterator parameter is passed, the library will use this "no-op" iterator instead and the elements of the array will remain unchanged.