I want to do something like as follows
_(data)
.map(() => /** ... */)
.reduce(function (modifier, doc) {
modifier.$set = modifier.$set || {};
modifier.$set.names = doc.names;
return modifier;
}, {})
.map(() => /** ... */)
.flatten()
However, it appears that after reduce, the chain breaks.
Is there a way to continue the chain from the value returned by reduce?
reduce()
method is not guaranteed to produce a collection (array, object, or string) upon which other methods could operate, therefore it makes no sense that it could be chainable by default.
From lodash documentation on lodash object ( _
):
Methods that operate on and return arrays, collections, and functions can be chained together. Methods that retrieve a single value or may return a primitive value will automatically end the chain returning the unwrapped value.
You can however explicitly enforce chaining by using _.chain()
. This would allow for single values and primitives to be explicitly returned within lodash wrapper for continued chaining.
So for your code that might look like:
_.chain(data)
.map(() => /** ... */)
.reduce(function (modifier, doc) {
modifier.$set = modifier.$set || {};
modifier.$set.names = doc.names;
return modifier;
}, {})
.map(() => /** ... */)
.flatten()
The lodash docs say that reduce() is not chainable. See here: "The wrapper methods that are not chainable by default are: ... reduce" https://lodash.com/docs#_
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