To clear the display after result when input is loaded again - calculator

Question

Here after the result is loaded and try to input the next input it just get appended with the result, but the display should be cleared for the second calculation. Any help will be appreciated.
var arr=[];
var input=0;
function numberBtn(arg){
if ( document.getElementById("currentValue").innerHTML ==="ERROR" || (document.getElementById("currentValue").innerHTML == "0"))
{
document.getElementById("currentValue").innerHTML = "";
}
input += arg;
document.getElementById("currentValue").innerHTML += arg;
}
function calculate(val){
if(input !== 0){
addToArr(input);
}
var answer = val[0];
var divideZero =0;
var i=2
switch(arr[i-1]){
case '+':
answer= Number(val[i-2]) + Number(val[i]);
break;
case '-':
answer-= val[i];
break;
case '/':
if (val[i] == 0) divideZero = 1;
else answer = answer / val[i];
break;
case'*':
//console.log(value,'before multiply');
answer = answer * val[i];
// console.log(val[i],'after multiply');
break;
case'%':
if (val[i] == 0) divideZero = 1;
else{
var q= val[i-2]/val[i];
answer= val[i-2] - (val[i] * Math.floor(q));
}
break;
case'+/-':
answer= -answer;
break;
}
if ( divideZero === 1) {
clearAll();
document.getElementById("currentValue").innerHTML = "ERROR";
}
else
{
document.getElementById("currentValue").innerHTML = answer;
input = answer;
arr = [];
}
}
function addToArr(input){
arr.push(input);
}
function clearAll() {
arr = [];
input = 0;
document.getElementById("currentValue").innerHTML = "0";
}
function operatorBtn(arg){
if (input !== 0) {
addToArr(input);
addToArr(arg);
document.getElementById("currentValue").innerHTML +=arg;
input = 0;
}
}