CODEWITHSUNDEEP
javascript
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Reputation: 15652

Why isn't this javascript code working?

http://jsfiddle.net/LU3pE/

I want the function to make the arguments into a single string and return it. What have I done incorrectly?

function cooncc(divider, lastdiv){
    var returner;
    for (var i = 0; i < (arguments.length - 2); i++)
    {
        returner += arguments[i+2] + divider;
    }
    returner -= divider;
    returner += lastdiv + arguments[arguments.length - 1];
    return divider;
}
var output = cooncc(", ", ", and ", "Andy", "Becky", "Caitlin", "Dave", "Erica", "Fergus", "Gaby");
document.body.innerHTML = "<h1>" + output + ".</h1>";

Upvotes: 0

Views: 95

Answers (6)

Shadow Wizard
Shadow Wizard

Reputation: 66399

Your function needed major rewrite, here is working version:

function cooncc(){
    var arrWords = new Array();
    var divider = arguments[0];
    var lastdiv = arguments[1];
    for (var i = 2; i < arguments.length; i++)
    {
        var curWord = arguments[i];
        if (i == arguments.length - 1 && i > 2) {
            arrWords[arrWords.length - 1] += lastdiv + curWord;
        }
        else {
            arrWords.push(curWord);
        }
    }
    return arrWords.join(arguments[0]);
}

(no change in calling it)

Updated jsFiddle: http://jsfiddle.net/yahavbr/LU3pE/1/

Upvotes: 0

R. Martinho Fernandes
R. Martinho Fernandes

Reputation: 234354

You're doing lots of things wrong. Here's a breakdown of what you need to fix:

  1. You're returning divider! Change that to returner:

    return returner;

  2. This line does not do what you expect:

    returner -= divider

    You cannot subtract strings from strings unless they're numbers, and that's why you get NaN (not-a-number) in the output.

    Try:

    returner = returner.substring(0,returner.lastIndexOf(divider));

  3. You did not initialize returner. That will get you a "undefined" into your string. Initialize to the empty string:

    var returner = "";

  4. You're adding the last string twice: once in the loop and then one last time with the last divider. Just stop the loop one earlier:

    for (var i = 0; i < (arguments.length - 3); i++)

  5. Finally, think about what happens if you call it like this with only one string to concatenate: cooncc(", ", ", and ", "Andy"). You can solve this with a guard clause:

    if(arguments.length == 3) return arguments[2];

Upvotes: 4

deceze
deceze

Reputation: 521995

Sidestepping the question, but there are more elegant ways to do what you want to do:

var names = ["Andy", "Becky", "Caitlin", "Dave", "Erica", "Fergus", "Gaby"];
var divider = ', ';
var lastDivider = ' and ';

var concatNames = names.slice(0, -1).join(divider) +
                  lastDivider +
                  names[names.length - 1];

alert(concatNames);

https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/join
https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/slice

Upvotes: 0

user26901
user26901

Reputation:

you need to initialize returner and you can't use -= with divider. If you put alert(returner) after the returner -= divider you get NaN back. try this fix.

function cooncc(divider, lastdiv){
    var returner = "";
    for (var i = 0; i < (arguments.length - 3); i++)
    {
        returner += arguments[i+2] + divider;
    }
    returner = returner.substring(0,returner.lastIndexOf(divider));
    returner += lastdiv + arguments[arguments.length - 1];
    return returner;
}
var output = cooncc(", ", ", and ", "Andy", "Becky", "Caitlin", "Dave", "Erica", "Fergus", "Gaby");
document.body.innerHTML = "<h1>" + output + ".</h1>";

Upvotes: 0

ivy
ivy

Reputation: 5559

Initialize returner? 

var returner = "";

And you can't do with strings:

returner -= divider

Upvotes: 0

darioo
darioo

Reputation: 47183

Make the arguments into a single string? Do you mean you want this output?

, , and AndyBeckyCaitlinDaveEricaFergusGaby

If, yes, you can use this modification of your code:

function cooncc(divider, lastdiv){
    var returner = "";

    console.log(arguments.length);

    for (var i = 0; i < arguments.length; i++) {
        returner +=  arguments[i];  
    }

    return returner;
}
var output = cooncc(", ", ", and ", "Andy", "Becky", "Caitlin", "Dave", "Erica", "Fergus", "Gaby");
document.body.innerHTML = "<h1>" + output + ".</h1>";

Oh, and if you change the last bit in your code from return divider to return returner, you get

NaN, and Gaby

although, I'm not sure if this is what you want.

Upvotes: 0

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