Question

This probably has been asked before but all I can find are questions regarding C and Bash etc.

Basically I’m having a really hard time getting my head around function parameters and what they reference.

I know that you usually set paramters when you call the function e.g. doSomething(3,'Hello') etc, but when I read code from tutorials like so;

window.onload = initAll;

function initAll() {
    if (document.getElementById) {
        for (var i=0; i<24; i++) {
            setSquare(i);
        }
    }
    else {
        alert("Sorry, your browser doesn't support this script");
    }
}

function setSquare(thisSquare) {
    var currSquare = "square" + thisSquare;
    var colPlace = new Array(0,0,0,0,0,1,1,1,1,1,2,2,2,2,3,3,3,3,3,4,4,4,4,4);
    var colBasis = colPlace[thisSquare] * 15;
    var newNum = colBasis + getNewNum() + 1;

    document.getElementById(currSquare).innerHTML = newNum;
}

function getNewNum() {
    return Math.floor(Math.random() * 15);
}

Where is setSquare() getting the parameter of thisSquare from?

Answer 1

In your first function initAll(), you are calling setSquare(i). In this case, the i is the parameter. According to initAll(), i is a number in the for loop. Essentially what’s happening is you’re calling setSquare for each square number 0 to 24.

The setSquare() function has renamed the i to thisSquare. Now anywhere inside the setSquare() function, thisSquare is set to the same value that i had before.

Hope that helps, good luck.