Manipulate Array

function solve(manipulatedArr, commandsArr) {

    for(let i = 0; i < commandsArr.length; i++) {
        let commandArr = commandsArr[i].split(' ');

        if(commandArr[0] == 'add') {
            manipulatedArr.splice(commandArr[1], 0, Number(commandArr[2]));
            // ====================================================
        } else if (commandArr[0] == 'addMany') {
            commandArr.shift();
            let index = commandArr.shift();

            for(let i = 0; i < commandArr.length; i++) {
                commandArr[i] = Number(commandArr[i]);
            }

            manipulatedArr.splice(index, 0, ...commandArr);
            // ====================================================
        } else if (commandArr[0] == 'contains') {
            if(manipulatedArr.includes(Number(commandArr[1]))) {
                console.log(manipulatedArr.indexOf(Number(commandArr[1])));
            } else {
                console.log(-1);
            }
            // ====================================================
        } else if(commandArr[0] == 'remove') {
            manipulatedArr.splice(commandArr[1], 1);
            // ====================================================
        } else if (commandArr[0] == 'shift') {
            for(let i = 0; i < commandArr[1]; i++) {
                let shiftedEl = manipulatedArr.shift();
                manipulatedArr.push(shiftedEl);
            }
            // ====================================================
        } else if (commandArr[0] == 'sumPairs') {
            let resultArr = [];
            for(let i = 0; i < manipulatedArr.length; i+= 2) {
                let sum = manipulatedArr[i] + manipulatedArr[i + 1];
                resultArr.push(sum);
            }
            manipulatedArr = resultArr;
            // ====================================================
        } else if (commandArr[0] == 'print') {
            manipulatedArr = manipulatedArr.join(', ');
            console.log(`[ ${manipulatedArr} ]`);
            break;
        }
    }
}