使用jQuery通过数组索引和名称属性设置文本框值

Question

$("[name=imageheight]") return following array of textboxes

I know i can get the value of textbox by its index like

How do i set the value of textbox on index 0. i have tried this but it gives me a error

Answer 1

$('[name=imageheight]').eq(0).attr('value', '250')

Answer 2

 $('input').eq(0).val("new value") 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input type="text" /> 

Answer 3

您可以使用

$('[name=imageheight]').eq(0).val(250)

Answer 4

Explanation:

jQuery returns a jQuery object which has a val function, which returns its value if no parameter is passed and sets its value if a parameter is passed. However, the [0] of a jQuery object is an element and is not a jQuery object. As a result, it does not have a val() function. You can work with that as well, if you set its value attribute, like this:

jQuery("input[name=firstname]")[0].value = 250; Also, you can bypass jQuery if you want, like this:

document.querySelectorAll("input[name=firstname]")[0].value = 250;

Answer 5

The problem in your code is, $("[name=imageheight]")[0] will not return an jQuery object. So you cannot use .val() over that node. But, $("[name=imageheight]").eq(0) will return the node as a jQuery object over which you can use .val()

 $('input').eq(0).val("new value") 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input type="text" /> 

Answer 6

Actually $("[name=imageheight]") returns jquery object of that element. that jquery object contains javascript DomElement object you can access DomElement object from jQuery object by $('....')[0]

$("[name=imageheight]")[0].value obviously return value because value is propert of DomElement.

You can set value by $("[name=imageheight]")[0].value= 250; in DomElement object

val() is setter and getter method of jQuery you have to fetch first element onlu by .first() method or ':first' selector.

$("[name=imageheight]:first").val(250);

or

$("[name=imageheight]").first().val(250);