Have you ever caught yourself doing something like this?
Problem: To get the class where all students' name contains the letter 'J':
const studentsByClass = {
class_1: ['john', 'mark', 'josh'],
class_2: ['jeash', 'jack', 'jean']
}
const result = Object.fromEntries(Object.entries(studentsByClass)
.filter(([className, students]) => {
return students.every(studentName => studentName.includes('j'))
}))
It's pretty long right? Pretty hard to read as well.
Recently, I've found a way to make this readable. I've found this article from freecodecamp.org about pipe function.
It goes like this:
const pipe = (...fns) => (x) => fns.reduce((v, f) => f(v), x);
const toEntries = val => Object.entries(val)
const filterClass = entries => {
return entries.filter(([className, students]) => {
return students.every(studentName => studentName.includes('j'))
})
}
const fromEntries = entries => Object.fromEntries(val)
pipe(
toEntries,
filterClass,
fromEntries,
)(studentsByClass);
This has really helped me with the long lines of code. But I am not yet comfortable with the functional javascript. So I made my own version:
const pipe = (initial, fns) => fns.reduce((v, f) => f(v), initial)
How to use it:
const pipe = (initial, fns) => fns.reduce((v, f) => f(v), initial)
const toEntries = val => Object.entries(val)
const filterClass = entries => {
return entries.filter(([className, students]) => {
return students.every(studentName => studentName.includes('j'))
})
}
const fromEntries = entries => Object.fromEntries(val)
pipe(studentsByClass, [
toEntries,
filterClass,
fromEntries,
]);
But, I usually do it like this to avoid cluttered codebase.
const pipe = (initial, fns) => fns.reduce((v, f) => f(v), initial)
const filterClass = entries => {
return entries.filter(([className, students]) => {
return students.every(studentName => studentName.includes('j'))
})
}
pipe(studentsByClass, [
val => Object.entries(val),
val => filterClass(val),
val => Object.fromEntries(val)
]);
Sources/Reads
freecodecamp
github
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