Javascript function not getting a value from an input box and loop through an array

getElementsByName returns an array and your function is expecting a single element, you need to access the first element like this:

checkAmount(document.getElementsByName(\'ammount\')[0]); 

Change the ting.value to boxes.length in the for loop:

function checkAmount(ting)  {  
var boxes = document.getElementsByTagName("input");  
for (var i = 0; i < boxes.length; i++)   {  
        boxes[i].checked = (boxes[i].name == "vote[]") ;  
  }  
}

Try this:

boxes.item(i).checked = checked

sorry not sure how to insert javascript into the post

are you posting your real code? If so, you realize that you are spelling 'amount' wrong in your function call?

From your statement "gather an amount from an input box" I think you expect ting to be a number entered into a text box and so you are calling a function that expects a number with a value that should resolve to an array of form element objects?

var m = document.getElementsByName("amount");

m will be an array!

in other words, it might work better if you made sure you were passing a number when you call checkAmount:

checkAmount(documents.forms[0].amount.value)

or:

checkAmount(documents.getElementsByName("amount")[0].value)

It would help a lot if you post the actual HTML and actual javascript code.

There are several problems with the code you posted, as indicated by the previous answers and replies. Try something like this:

function checkAmount(ting)  {  
    var boxes = document.getElementsByTagName("input");  
    for (var i = 0; i < ting.value && i < boxes.length; i++)   {  
        if (boxes[i].name == "vote[]")   {  
            boxes[i].checked = true;  
        }  
    }  
}

Called like this:

uncheckAll(); 
checkAmount(document.getElementsByName(\'ammount\')[0]);

Now you are safe from array out of bounds errors no matter the value typed in the input field and the call to checkAmount should work.

Try using

checked=checked

instead of

checked=true