This basically boils down to the main differences between Aura and LWC. Lets visit some of the practical differences:
- Aura is not truly component based framework. For example, when you define some styles on class
my-class in 1 component, then those styles would apply to some other component in same window which uses the same class
This would not happen in LWC because of the concept called shadow DOM (closed mode by default).
Aura is not something derived from global standard. LWC on the other hand is implemented on top of standard Web Components
Aura is not natively supported by browser. So, salesforce has to convert the tags in client machine which was done through
aura_prod.js. If you observe what you are getting from lightning server, you will notice that you will not get any HTML markup.
aura_proj.js is responsible for creating HTML elements at runtime for every transaction. This is the main reason why Aura does not has good performance.
LWC on the other hand is natively supported by all browsers because its built on standard web components. Hence there is no additional overhead (like that of Aura).
Aura is a 2-way binding framework and LWC is a 1-way framework.
Using Aura, we can create components dynamically but in LWC dynamic creation of components is not allowed (not exposed).
And the main difference is
- Aura tries to modify the same object/array in
LWC simply creates a new assignment thereby creating new memory allocation. It does not really spend time checking which property in object or item in array might have changed. This is the main reason when
api variables are set by the parent component, it is no longer allowed to be modified by the child component which has implemented
Although we have many other differences, these are the main ones. Also the main similarity between them is:
Both Aura and LWC have same secures variables like
document etc and have access to same methods on them.
Note: Aura is using LWC components in most of the base components behind the scenes (as confirmed by salesforce support - UNOFFICIALLY) - for example, datatable. However this has only solved the performance problems of Aura upto certain extent but still true nature of Aura is still same as above.
Considering all these reasons, logically its just not possible to use Aura inside LWC.