向文本字段JavaScript添加变量

Question

For my Javascript assignment I have to make a slot machine.

The one part I can't get is adding my totalCredits Variable to my textfield.

It just puts the variable beside the credits instead of adding them. (want to add 30 + 2 but I get 302)

I have tried parseFloat and parseInt both give me "ReferenceError: invalid assignment left-hand side"

This is the function

    function checkForWin() {

     if (bet1 == true && symbols[rng1].color == symbols[rng2].color && symbols[rng2].color == 
        symbols[rng3].color && symbols[rng1].color == symbols[rng3].color) {

document.getElementById("message").innerHTML = "Same Color You Win 2 Credits";
            totalCredits = totalCredits + 2;

            parseInt(document.getElementById('credits').value) = totalCredits;
            console.log(totalCredits);

     };

Code : https://jsfiddle.net/Socha/ndLn73bw/

Answer 1

Change it as below

            total = parseInt(totalCredits) + 2;

            document.getElementById('credits').value = total;