Problem

Declare two variables in function A, bring them to function B, then bring them back to function A

Solution

let funcA = (x = 0, y = 1) => {
    console.log(`funcA`,x, y)
    return [x, y];
}

let funcB = () => {
    let [x, y] = funcA();
    console.log(`funcB`,x,y);
    funcA(x, y)
}

funcB();

Old solution

let funcA = (values) => {
    console.log(`funcA values recieved: `, values)
    if(values && values.length) {
        console.log(`funcA returning`, values, `\n`)
        return values;
    }
    let x = 0;
    let y = 1;
    console.log(`funcA returning`, [x, y], `\n`)
    return [x, y];
}

let funcB = (values) => {
    console.log(`funcB: `, values, `\n`)
	return values;
}

console.log(
	funcA(funcB(funcA()))
);