document.getElementsByTagName not working

问题

I would like to use document.getElementsByTagName('input') to set as required (or unset it) for a list of inputs. is it possible?

I've tried:

document.getElementsByTagName('input').required = false;

or (for a different purpose)

document.getElementsByTagName('input').value = ""

but it doesn't seem work.

Moreover: is it possible to catch a certain type of input (i.e. text or radio)?

Thank you!!! ObOnKen

回答1:

getElementsByTagName() returns a collection of elements so you need to iterate over the collection...

var elements = document.getElementsByTagName('input');

for(var i = 0; i < elements.length; i++)
{
    if(elements[i].type == "text")
    {
        elements[i].value = "";
    }
}

回答2:

getElementsByTagName() returns a live HTMLCollection. If you want to do something to each item returned, you'll have to explicitly iterate across them:

var inputs = table.getElementsByTagName('input'); 
for (var i = 0; i < inputs.length; i++) { 
    inputs[i].required = false;
}

However, if you use some libraries, you may be able to operate on each of the contents of a collection (or, as some of the libraries call them, selection) en-masse with a syntax as you seem to expect.

回答3:

You should use for loop for iterating all inputs, because document.getElementsByTagName returns a HTMLCollection of elements with the given tag name.

var values = document.getElementsByTagName('input');
for (var i = 0; i < values.length; i++) {
    values[i].required = false;
}

To catch a certain type of input:

var textInput = document.querySelector("input[type=text]");

querySelector returns the first element within the document.

来源：https://stackoverflow.com/questions/35661807/document-getelementsbytagname-not-working

标签

javascript