Javascript: Editing the Value of a Form Field?

Question

This is my html:

<div class="myFormField">
     <input type="text" class="myFormField city" value="" name="city" id="city">
</div>

I'm trying the to set the following but it's not working, it's returning undefined when I test with alerts:

document.getElementsByClassName("myFormField city").value = "New York";

Any help is appreciated thanks!

Answer 1

It should be:

document.getElementsByClassName("myFormField city")[0].value = "New York";

Please take a look at the documentation for getElementsByClassName :

"Returns a set of elements which have all the given class names."

getElementsByClassName returns a set of elements, so you need to access a specific element in that set to give it a value - first element of the set being [0] , second is [1] etc.

jsFiddle here.

Answer 2

document.getElementsByClassName("myFormField city")

will return array of elements

so use

document.getElementsByClassName("myFormField city")[0].value

Answer 3

Please note that the document.getElementsByClassName gets the array of elements with classname given . So your code should be,

document.getElementsByClassName("myFormField city")[0].value = "New York"

Answer 4

你也有身份证

document.getElementById("city").value = "New York";