如何将更改的输入值作为参数传递给另一个函数

Question

I have an input text field where the value could be incremented or decremented with plus and minus buttons.

I need to pass the value of this input field as a 3rd parameter to a function being called onclick in another button (all elements in the page loaded in the same time).

How do I do this with Javascript , not jQuery? If I simply pass the name of the function, I get its body.

JSFIDDLE

html:

<input type="button" onclick="updateQuantity('test','add')" value="+" />
<input type="button" onclick="updateQuantity('test','not')" value="-" />
<input type="button" onclick="getUpdatedQty()" value="just proof that I can get value of quantity" />
<input type="button" onclick="passData('test', 2, 2)" value="button passing the data" />

js:

function updateQuantity(ID, action){

var prodQty = document.getElementById(ID);
var maxQty = 3;

    if(action === 'add') { 
        prodQty.value++; 
        if(prodQty.value > maxQty) { prodQty.value = maxQty }

    } else { 
        prodQty.value--; 
        if(prodQty.value <= 0) { prodQty.value = 1 }
    } 
} 

function passData(p1, p2, p3) {
    alert('First: '+p1 + ', Second: ' + p2 +', Third: '+ p3);
}

function getUpdatedQty() {
    var prodQty = document.getElementById('test'); alert(prodQty.value);
}

Answer 1

I've found the solution, maybe someone else will need this in the future:

html:

<input type="text" name="quantity" id="test" value="1" />
<input type="button" onclick="updateQuantity('test','add')" value="+" />
<input type="button" onclick="updateQuantity('test','not')" value="-" />
<input type="button" onclick="passData('test', 2, getUpdatedQty)" value="button passing the data" />

js:

function updateQuantity(ID, action){
var prodQty = document.getElementById(ID);
var maxQty = 3;

        if(action === 'add') { prodQty.value++; 
            if(prodQty.value > maxQty) { prodQty.value = maxQty }

         } else { prodQty.value--; 
                if(prodQty.value <= 0) { prodQty.value = 1 }
         } 
    } 

    function passData(p1, p2, p3) {

    alert('First: '+p1 + ', Second: ' + p2 +', Third: '+ p3());
    }

function getUpdatedQty() {
    var prodQty = document.getElementById('test'); return prodQty.value;
}

jsFiddle