Just last night I found this excellent introduction to the Lambda Calculus by Gabriel Lebec [1]. It's one of the best I've come across and covers briefly history, building up combinators (using Smullyan's names) leading up to implementing Church encodings and gives Javascript equivalents (or approximations when not possible). The slides themselves are also very aesthetically pleasing, Gabriel has a good sense of colour and design

[1] https://youtu.be/3VQ382QG-y4