How to convert a string to a integer inside a function?

Question

I want to convert an input id string in a integer. I am testing this js functions, despite getPrice is working, getQty gives me "undifine" instead of a number. What is wrong?

function getPrice() {
var price = document.getElementById("priceTshirt").innerHTML;
document.getElementById("total-1").innerHTML = price;
}

getPrice();


function getQty() {
var qty = document.getElementById("qty1").innerHTML;
document.getElementById("demolish").innerHTML = qty;
qty = qty.parseInt;
}

getQty();

Answer 1

Qty1 is an input element, it doesn't have innerHTML. You should get the value instead:

function getQty() {
    var qty = document.getElementById("qty1").value;
    document.getElementById("demolish").innerHTML = qty;

    return qty;
}

and you can set the total price using the quantity returned by the getQty function:

function getPrice() {
    var price = parseInt(document.getElementById("priceTshirt").innerHTML);
    document.getElementById("total-1").innerHTML = price * getQty();
}