arrayManipulator with switch

function arrManipulator(arr,elements){
    for(let row of elements){
        row=row.split(" ")
        let command=row.shift()
        let firstNum=Number(row.shift())
        if(command!=='print'){
            switch(command){
                case "add":
                    add(arr,firstNum,row)
                break;
                case "remove":
                    remove(arr,firstNum)
                break;
                case "addMany":
                    addMany(arr,firstNum,row)
                break;
                case "contains":
                    contains(arr,firstNum)
                break;
                case "shift":
                    shift(arr,firstNum)
                break;
                case "sumPairs":
                    arr=sumPair(arr,)
                break;
            }
        }
        else{
            break;
        }
    }
    console.log(`[ ${arr.join(", ")} ]`)

    function add(arr,index,element){
       return arr.splice(index,0,Number(element))
    }

    function remove(arr,index){
       return arr.splice(index,1)
    }

    function addMany(arr,index,row){
        row=row.toString().split(",")
        for(let num of row.reverse()){
            arr.splice(index,0,Number(num))
        }
    }

    function contains(arr,searchedNum){
        if(arr.includes(searchedNum)){
            console.log(arr.indexOf(searchedNum))
        }
        else{
            console.log(-1)
        }
    }

    function shift(arr,count){
        for(let i=0;i<count;i++){
            arr.push(arr.shift())
        }
    }

    function sumPair(arr){
        let sum=[]
        if(arr.length%2!==0){
            arr.push(0)
        }
        while(arr.length>0){
            let firstPair=arr.shift()
            let secondPair=arr.shift()
            sum.push(firstPair+secondPair)
        }
        return sum
    }

}