How come the following happens in the console? or am i misusing the indexOf?
document.forms:
[
<form id="form-0" name="form-0">…</form>
,
<form id="form-1" name="form-1">…</form>
,
<form id="form-2" name="form-2">…</form>
]
document.forms.indexOf["form-0"]:
TypeError: Cannot read property 'form-0' of undefined
Document.forms is a collection. If you want the number of a form - as indicated in your comments -, the question remains: at which moment do you want that number? Anyway, you could create an array of forms:
var allforms = document.getElementsByTagName('form'),
formsArray = [];
for (var i=0;i<allforms.length;i++){
if (allforms[i].id.match(/\d+$/)){
var indexval = parseInt(allforms[i].id.replace(/(.+)(\d+)$/,'$2'),10);
formsArray[indexval] = allforms[i];
}
}
Now you have an Array containing references to all forms, and for each form an index value that reflects the form number you gave it via it's id. So: formsArray[0] contains a reference to forms['form-0'], formsArray[1] to forms['form-1'] etc.
You've used the wrong syntax... indexOf is a method, so it should use parenthesis, not brackets.
someString.indexOf("form-0")
With an object, you can simply request the object using brackets:
document.forms["form-0"]
document.forms is an HTMLCollection. It is not an array. As such, it does not have an indexOf method.
You can convert it using Array.prototype.slice.call:
var formsArr = Array.prototype.slice.call(document.forms);
Note, however, that indexOf is not universally supported. I'm not entirely sure what you're trying to do, however, so it may well not be the necessary approach anyway.
If you're trying to get the element by its ID, just use the ID directly.
document.forms['form-0'];
If you want its index, it would seem that you already have it in the ID. Just remove the "form-" part.
var index = 'form-0'.replace('form-','');
Or if you have the element, do the same via its ID property:
var myform = document.forms['form-0'];
var index = myform.id.replace('form-','')
If you want to access the elements of a form using javascript, then you have to use this: document.myform.elements[i], where i is the position of the element. You may refer this Javascript Form Objects - Properties and Methods tutorial. indexof is a method of javascript string object.
