[Shiro]

I put together a DOM script for my company the other day. While doing it, I ran into a data-type problem. I know enough to know that my datatypes were wrong (or at least I figured that out), and I figured out how to convert them to the same datatype in order to make it work, but I don't know enough to know what the original datatypes were.

I had one function called from two places. In the function was a 'switch'. One variable, a number, was passed to the function, and then that variable was used to execute the switch statement.

I got the variable passed to the function in two different ways. The first way was through a for loop.

for(var i = 0; i < variable.length; i++)
{
    if(i = someVariable)
    {
        return i;
    }
}

I was the variable I passed to the function.

The other one I got was through a drop down menu. I wont put the whole code in here, but I had a <select>tag with some <options> tags in it, and the value for each of the <option> tags was a number. This time I called the function using the onclick event listener in the <select> tag. I passed the value of this.value to the function.

So in the first case, I was passing 'i', in the second case I was passing 'this.value' from a select tag.

The datatypes didn't match. I eventually got around the problem by converting both to text, and converting the number values in the 'switch' statement to strings. It worked, but as I say, I don't think it was ideal.

So my questions:

1) What were my datatypes from these two methods?
2) How could I have converted each of them to the other data type?


Thanks to anyone who answers this! As I say, its not imperative in that I have already found a work around, but I want to understand better so that I can become a better programmer.

[Hunch]

Forgive me if I've misunderstood your questions. Your initial explanation was a bit hard to follow.

1. The original data types

In the loop example, i is a Number (there are no specific int or float types in javascript).

In the select tag example, it's a String, even though it is a numeric character. You can check this if you want with the following:

<select onChange="alert(typeof(this[this.selectedIndex].value))">
<option>1</option>
<option>2</option>
</select>

(the typeof operator returns the data type of its operand)

2. Conversion

The easiest way to convert types in Javascript is to simply use the constructor called as a function, e.g.

var numberValue = Number(stringValue); // Convert string to number
var stringValue　= String(numberValue); // Convert number to string

These aren't terribly efficient methods and there are other ways. For example you can convert a string to a number by performing a non-value-altering mathematical operation on it such as:

var numberValue = stringValue*1;
var numberValue = stringValue-0;
// or other similar kinds of operations

Or you could turn a number into a string by using the concatenation operator:

var stringValue = numberValue + "";

I'm sure you can come up with a number of other ways, these are just a few.

[Shiro]

Thank you sir. Sorry for the unclear explanation, it was kind of hard to explain what I was getting at, but you answered my questions exactly the way I was looking for. Gracias!