Question

I’m still working on a program and I have a problem. The code is here:

function Calculate(){
    var elev = [];
    var inputs = document.getElementsByName("txt");
    for(i=0; i<inputs.length; i++) {
    elev[i] = {
        "Value": inputs[i].value,
        "Used": false
    };
}

    for(j=0; j<=10; j++) {
            var r = Math.floor(Math.random() * 20);

            if (elev[r].Used) {             //1st number
                for(var a=0; a<=21; a++) {
                    if (!elev[a].Used) {
                        elev[r].Value = elev[a].Value;
                        break;
                        }
                    else {continue; }
                    }
                }
                ...
                }
            }


            elev[r].used = true;
            doument.write(elev[r].Value);
            ...
        }
}

First of all, I have 22 imports to the var inputs[i].value (later elev[i]) in my HTML document. I want it to use all of the ‘elev’ arrays once, but I see (in my document.write as I clipped out here) it uses some of them twice and some of them isn’t even used. How can I fix that?

Problem solved by using the Fisher-Yates shuffle

Answer 1

Let me point out several problems with your script

First of all this section

for(i=0; i<inputs.length; i++) {
   elev[i] = inputs[i].value;
   elev[i].used = false;
}

You are assigning the value to the array but it is of type String. String does not get the properties.

The following code will work

var obj = {};
obj.SomeProp = true;

But if you do so

var str = "";
str.SomeProp = true;

attempt to use str.SomeProp will always return undefined
The code if (elev[r].used) will always be evaluated to false (because 0, empty string, false, null and undefined behaves as false in if operator in JavaScript)
So I suggest you to refactor your code into

for(i=0; i<inputs.length; i++) {
    elev[i] = {
        "Value": inputs[i].value,
        "Used": false
    }; // Pay attention, I added an object and Used property starts with an uppercase letter.
    // Then further in the code you'll use elev[index].Value in order to use the value
}

And finally the block if (elev[aa].used = false) will not throw exception, but this is a error.

Consider the following snipped

var someVal = true;
if (someVal = false)
    alert("That's wierd");
alert(someVal);

It will work because you are assigning the value false to the someVal variable and this instruction is evaluated to true. Some the alert with message That's wierd will appear. Furthermore, you’ll notice that the someVal‘s value is false.
This snipped uses the equality operator which will be evaluated to false and the first alert will not work out. However there is a problem too. A stylistic one. Never check the value for false, especially in JavaScript.

var someVal = true;
if (someVal == false)
    alert("That's wierd");
alert(someVal);

The correct snippet must look like this.

var someVal = true;
if (someVal)
    alert("There you go!");
alert(someVal);

P.S.

You get the variable aa from nowhere. Where does it come from? It must be undefined. What did you want?
Concatinated values of two numbers? The sum of them?

EDIT:

Just a few notices.

1) Use for (var a = 0; a < someConstant; a++) syntax. Don’t forget to add var keyword.

2) Use proper indention, i.e.

if (someCondition){
    // Some instruction
    for (var i = 0; i < 10; i++) {
        //more indention
    }
}

3) Don’t use empty else block.