The resources that I think are most relevant to your projects
Observable Plot - General:
Observable Plot - Inputs:
These functions and methods are super useful for cleaning and filtering data in Javascript!
Array.map - runs once for each item in an array. The function call inside allows you to change each item in the array.
Array.forEach - similar to above, runs for each item in an array. Use this if you want to actually change the original array. Use the map function if you want to return a new array
Array.filter - This does not affect the original array you are using, but instead returns a new array. Allows you to easily remove values from an array that don't meet specific conditions.
Array.slice - Allows you to take a subset of the original array
Array.concat - allows you to merge multiple arrays. If this doesn't meet your suited purpose, look into d3's d3.merge function
String.split - split string into multiple pieces based on some anchor character
let name = 'Hameed, Noor';
name.split(',')
//will return an array with ['Hameed', 'Noor']
d3.groups - used to group an array by a certain property
If the above methods don't meet your needs, it's likely that d3.js (an external library) will have the right tools, see all array methods here