Lodash _.identity Function: Usage and Examples

'_.identity' is a function in the Lodash library that simply returns the first argument it receives. It's often used as a default function in other Lodash methods where a function is expected, but no specific operation needs to be performed.

For example, if we have an array of values and want to filter out any values that are falsy, we could use the '.compact' method and provide '.identity' as the function argument:

const values = [0, 1, '', 'hello', false, undefined, null];

const filteredValues = _.compact(values, _.identity);
// filteredValues = [1, 'hello']

In this case, '.identity' is used as a callback function to determine whether each value is truthy or falsy. Since '.identity' simply returns the value itself, any truthy values will be kept in the filtered array.