08. Array Manipulator

function arrayManipulator(numbers, commands) {
    while (commands.length !== 0) {
        let command = commands.shift().split(' ');
        if (command[0] === 'add') {
            numbers.splice(Number(command[1]), 0, Number(command[2]));
        } else if (command[0] === 'addMany') {
            let input = command.slice(1).map(Number);
            let index = input.shift();
            for (let i = index; i < input.length + index; i++) {
                numbers.splice(i, 0, input[i - index]);
            }
        } else if (command[0] === 'contains') {
            console.log(numbers.indexOf(Number(command[1])));
        } else if (command[0] === 'remove') {
            numbers.splice(Number(command[1]), 1);
        } else if (command[0] === 'shift') {
            for (let i = 0; i < Number(command[1]); i++) {
                numbers.push(numbers.shift());
            }
        } else if (command[0] === 'sumPairs') {
            let x = Math.floor(numbers.length / 2);
            for (let i = 0; i < x; i++) {
                numbers[i] += numbers[i + 1];
                numbers.splice(i + 1, 1);
            }
        } else if (command[0] === 'print') {
            console.log(`[ ${numbers.join(', ')} ]`);
        }
    }
}

РЕШЕНИЕ СЪС SWITCH:

function arrayManipulator(numbers, commands) {
    while(commands.length !== 0){
        let command = commands.shift().split(' ');
        switch (command[0]){
            case 'add':
                numbers.splice(Number(command[1]), 0, Number(command[2]));
                break;

            case 'addMany':
                let input = command.slice(1).map(Number);
                let index = input.shift();
                for (let i = index; i < input.length + index; i++) {
                    numbers.splice(i, 0, input[i - index]);
                }
                break;

            case 'contains':
                console.log(numbers.indexOf(Number(command[1])));
                break;

            case 'remove':
                numbers.splice(Number(command[1]), 1);
                break;

            case 'shift':
                for (let i = 0; i < Number(command[1]); i++){
                    numbers.push(numbers.shift());
                }
                break;

            case 'sumPairs':
                let x = Math.floor(numbers.length / 2);
                for (let i = 0; i < x ; i++){
                    numbers[i] += numbers[i + 1];
                    numbers.splice(i + 1, 1);
                }
                break;

            case 'print':
                console.log(`[ ${numbers.join(', ')} ]`);
                break;
        }
    }
}