Calculator

var textBox = document.getElementById("textBox");
var memory = 0;

if(typeof(Storage) != "undefined") {
    localStorage.setItem("number", memory);
}
else {
    alert("No 'localStorage' support");
}

function numButton(num) {
    if(typeof(textBox.value) != "string")
    {
        emptyBox();
    }
        textBox.value += num;
}

function emptyBox() {
    textBox.value = "";
}

function mathStuff(operator) {
    emptyBox();
    switch(operator) {
        case 'plus':
            memory = memory + Number(textBox.value);
            emptyBox();
            break;
        case 'minus':
            memory = memory - Number(textBox.value);
            emptyBox();
            break;
        case 'multiply':
            if(textBox.value === 0) {
                memory = Number(textBox.value) * 1;
            }
            else {
                memory = Number(textBox.value) * memory;
            }
            emptyBox();
            break;
        case 'divide':
            if(textBox.value === 0) {
                sysError('CAN NOT DIVIDE BY ZERO');
            }
            else {
                memory = Number(textBox.value) / memory;
                emptyBox();
            }
            break;
        case 'equal':
            textBox.value = memory;
            break;
        default:
            sysError('UNKNOWN ERROR');
            break;
    }
}

function otherButtons(task) {
    switch(task) {
        case 'ce':
            memory = 0;
            break;
        case 'c':
            textBox.value = "";
            break;
        default:
            sysError('UNKNOWN ERROR');
            break;
    }
}

function sysError(message) {
    // Add message to text box
    emptyBox();
    textBox.value += message;
}

document.getElementById("test").innerText += localStorage.getItem("number");

if(parseInt(memory) === 0 && memory > 0) {
    for(var i = 0; i < memory.length+1; i++) {
        if(i === 0) {
            // Remove 0 from the number
        }
    }
}