tupleCompare.tsx

// Compare two tuples for array.sort(); i.e. returns 1 if first item is larger; 2 if second item is larger, using the < operator.
// Similar to the std::tie comparison in c++: https://bajamircea.github.io/coding/cpp/2017/03/10/std-tie.html

type Comparable = number | string;
const tupleCompare = (a: Comparable[], b: Comparable[]) => {
    return a.reduce((prev, el, idx) => {
        if (prev != 0) return prev;
        else {
            if (el > b[idx]) return 1;
            else if (el < b[idx]) return -1;
            else return 0;
        }
    }, 0)
}


// Type-free, minified version for javascript
const jTupleCompare = (a, b) => a.reduce((p, e, i) => (p != 0) ? p : (e > b[i] ? 1 : (e < b[i] ? -1 : 0)), 0);


// Tests / usage
const assertEquals = (test, expected) => (test == expected) ? console.log("OK") : console.log(`Expected ${expected}, got ${test}`);

const customStruct1 = {
    prop1: 1,
    prop2: 2,
    prop3: 3
}

const customStruct2 = {
    prop1: 1,
    prop2: 3,
    prop3: 1
}

// order as most important to least important
const tieCustomStruct = (struct) =>[struct.prop1, struct.prop2, struct.prop3]

assertEquals(tupleCompare(tieCustomStruct(customStruct1), tieCustomStruct(customStruct2)), -1)
assertEquals(jTupleCompare(tieCustomStruct(customStruct1), tieCustomStruct(customStruct2)), -1)

assertEquals(tupleCompare(tieCustomStruct(customStruct2), tieCustomStruct(customStruct1)), 1)
assertEquals(jTupleCompare(tieCustomStruct(customStruct2), tieCustomStruct(customStruct1)), 1)

assertEquals(tupleCompare(tieCustomStruct(customStruct1), tieCustomStruct(customStruct1)), 0)
assertEquals(jTupleCompare(tieCustomStruct(customStruct1), tieCustomStruct(customStruct1)), 0)