A detailed explanation of the value and assignment examples of HTML elements in jquery _jquery

This article illustrates the value and assignment method of jquery to HTML elements. Share to everyone for your reference, specific as follows:

jquery gives the base control a value, an assignment

Textbox:

var str = $ (' #txt '). Val ();
$ (' #txt '). Val ("Set Lbl Value"); 
text box, text area:
$ ("#text_id"). attr ("Value", "");/empty contents
$ ("#text_id"). attr ("value", ' test ');/fill Content

Lable:

var str = $ (' #lbl '). Text ();
$ (' #lbl '). Text ("Set lbl Value");
var Valradio = $ ("input[@type =radio][@checked]"). Val ();
var item = $ (' input[@name =items][@checked] '). Val ();
var checkboxval = $ ("#checkbox_id"). attr ("value");
var selectval = $ (' #select_id '). Val ();

Multi-selection box checkbox:

$ ("#chk_id"). attr ("Checked", "");//Make it not checked
$ ("#chk_id"). attr ("Checked", true);//Check
if ($ ("#chk_id"). attr ( ' checked ') ==true)//judge whether it has been selected

Radio Group Radio:

Copy Code code as follows:

$ ("input[@type =radio]"). attr ("Checked", ' 2 '); Set the value=2 item to the current selected item

Dropdown box Select:

$ ("#select_id"). attr ("value", ' test ');//Set Value=test item is currently selected
$ ("<option value= ' test ' >test</option ><option value= ' test2 ' >test2</option>). Appendto ("#select_id")//Add drop-down Box option
$ ("#select_id") . empty ()//Empty dropdown box

Gets the value of a set of radio selected items named (items)

Copy Code code as follows:

var item = $ (' input[@name =items][@checked] '). Val ()//If not selected, val () = undefined

Gets the text of the Select selected item

var item = $ ("select[@name =items] option[@selected]"). Text ();
The second element of the Select Drop-down box is the currently selected value
$ (' #select_id ') [0].selectedindex = 1;

Radio the second element of a radio group is the currently selected value

Copy Code code as follows:

$ (' input[@name =items] '). Get (1). checked = true;

To reset a form:

$ ("form"). each (function () {
  . Reset ();
});

Add:

The value and assignment of jquery to form-form elements:

1. Select elements

$ ("#myid") effect is equal to document.getElementById ("myID"), but write a lot less characters.

If you need to convert a jquery object to an HTML element, you only need to take the No. 0 element. For example, $ ("#myid") returns a JQuery object, and $ ("#myid") [0] returns an HTML element

If you select all of the IMG elements, then write: $ ("img")

If you select a DIV element with a class= "TextBox" (<div class= "textbox" ></div>), then write: $ ("div. TextBox ")

Select element with MyAttr attribute $ ("div[myattr]")
Select the element $ ("div[myattr= ' MyClass ') with the MyAttr property and the property value equal to MyClass"
property is not equal to [myattr!= ' MyClass ']
Property starts with my [myattr^= ' my ']
Attribute ends with class [myattr$= ' class ']
property contains the CLA three characters [myattr*= ' CLA ']

If a selection returns multiple elements, and you want to apply some attributes to the element every time you return an element, you can write

$ ("div"). each (function ()
{
$ (this). CSS ("Background-color", "#F00 ″);
" Alert ($ (this). html ());
$ (this). Width ("200px");

2. The event

Add onload to the page event handling method

$ (function ()
{
alert ("The page structure is loaded, but some pictures may not have been loaded (in general, this event is sufficient)");

You can bind multiple onload event handling methods to a page

$ (function ()
{
alert ("I was executed first");
};
$ (function ()
{
alert ("I am second to execute");
};

Binding Special Events

$ ("#myid"). KeyDown (function ()
{
alert ("Trigger KeyDown event");
});

In addition to these commonly used, infrequently used events need to be bound by the Bind method

3. Element Attributes/Methods

Gets the height of an element, $ ("#myid"). Height ()
Gets the position of an element, $ ("#myid"). Offset () Returns an offset object, or $ ("#myid") if the top of the element position is taken. Offset (). Top, take left $ ("#myid"). Offset (). Left
Gets the innerHTML of an element, $ ("#myid"). HTML ()
Gets the innertext of an element, $ ("#myid"). Text ()
Gets the value of a text box, $ ("#myid"). Val ()
Gets the attribute of an element, $ ("#myid"). attr ("MyAttribute")

One of the basic features of these methods is that the values are represented without parameters, with parameters representing the settings (except for offset), such as

$ ("#myid"). Height ("20″");
$ ("#myid"). HTML ("<a href=" >asdasd</a>)
$ ("#myid"). Val ("ASDASD")

Be aware that offset is read-only.

Set properties for an element

Copy Code code as follows:

$ ("#myid"). attr ("width", "20%")

Read a property

Copy Code code as follows:

$ ("#myid"). attr ("width")

Specify multiple properties at once

Copy Code code as follows:

$ ("#myid"). attr ({disabled: "Disabled", Width: "20%", Height: "30″}")

Delete attribute

Copy Code code as follows:

$ ("#myid"). Removeattr ("Disabled")

Apply Style

Copy Code code as follows:

$ ("#myid"). AddClass ("MyClass")

Delete a style

Copy Code code as follows:

$ ("#myid"). Removeclass ("MyClass")

Add a Style

Copy Code code as follows:

$ ("#myid"). CSS ("height", "20px")

Add a set of styles

Copy Code code as follows:

$ ("#myid"). CSS ({height: "20px", Width: "100px"})

Note that if you add a style, the name of the style is the name in CSS, such as style= "Background-color: #FF0000 ″, the corresponding jquery notation is

Copy Code code as follows:

$ ("#myid"). CSS ("Background-color", "#FF0000 ″)

But when you add a set of styles, the name of the style is the CSS name in JavaScript, for example: Myid.style.backgroundColor = "#FF0000 ″, and the corresponding jquery notation is

Copy Code code as follows:

$ ("#myid"). CSS ({backgroundcolor: "#FF0000 ″}")

4. Find elements based on relationships

Find the next element of your own sibling

Copy Code code as follows:

$ ("#myid"). Next ()

Find all the elements below yourself at the same level as yourself

Copy Code code as follows:

$ ("#myid"). Nextall ()

Find the previous element of your own sibling

Copy Code code as follows:

$ ("#myid"). Prev ()

Find all the elements that are on your own at the same level

Copy Code code as follows:

$ ("#myid"). Prevall ()

Find your first generation of child elements

Copy Code code as follows:

$ ("#myid"). Children ()

Find your first parent element

Copy Code code as follows:

$ ("#myid"). Parent ()

Find all of your own parent elements

Copy Code code as follows:

$ ("#myid"). Parents ()

Example:

$ ("Div.l4″"). Parents (). each (
function () {
alert ($ (this). html ())
;

Will get all the parent elements of the Class=l4 div and alert out their HTML

Example:

Copy Code code as follows:

$ ("Div.l4″"). Parents ("Div.l2″"). each (function () {Alert ($ (this). html ());

Gets the Class=l4 's parent element, which must be a div, and its class=l2

All the methods mentioned here can be expressed with expressions, and the expression is written as reference to the first part

5. Maintenance elements

Add an element to the body

Copy Code code as follows:

$ ("Body"). Append ("<input type= ' text ' value= ' asd '/>")

The statement inserts this HTML into the body end tag, resulting in <input type= ' text ' value= ' ASD '/></body>

Copy Code code as follows:

$ ("Body"). Prepend ("<input type= ' text ' value= ' asd '/>")

The statement inserts this HTML into the body start tag, resulting in <body><input type= ' text ' value= ' ASD '/>

6.AJAX

Request a page with a Get method

Copy Code code as follows:

$.get ("http://www.google.com", "Q=jquery", function (data, status) {alert (data)})

Represents the request http://www.google.com, the parameter is Q, the value of the parameter is jquery, and after the request (whether successful or unsuccessful) executes the following function, which has two fixed parameters, data and status, Data is returned, status is the state of this request

Request a page with the Post method
$.post (...) parameter same get method

7. Other methods

$.trim (str) removes STR before and after spaces
$.browser returns the current user's browser type
$.browser.version returns the version of the current browser

8. Plugin

jquery support Plug-ins, http://jquery.com/plugins/has a lot of ready-made plug-ins, can also write their own
Write your own plug-ins, please refer to Http://docs.jquery.com/Core/jQ.....end#object and Http://docs.jquery.com/Core/jQuery.extend#object

1. Dropdown box:

var cc1 = $ (". FORMC select[@name = ' country '] option[@selected]"). Text (); Gets the text of the selected item in the Drop-down menu (note that there are spaces in the middle)
var cc2 = $ ('. FORMC select[@name = ' country '] '). Val (); The value of the selected item in the Drop-down menu is
var cc3 = $ ('. FORMC select[@name = "Country"]. attr ("id"); Gets the id attribute value of the selected item for the Drop-down menu
$ ("#select"). Empty ()//Empty Drop-down box//$ ("#select"). HTML (");
$ ("<option value= ' 1 ' >1111</option>"). Appendto ("#select")//option to add a drop-down box

A little explanation:

select[@name = ' country '] option[@selected] Represents the Name property,
and the attribute value is the option element with the selected attribute inside the Select element of ' country ';
It can be seen that a @ begins with a property that follows.

2. Radio Box:

$ ("input[@type =radio][@checked]"). Val (); Gets the value of the selected item in the Radio box (note that there are no spaces in the middle)
$ ("input[@type =radio][@value =2]"). attr ("Checked", ' checked ');//Set the checkbox value=2 selected. ( Note that there are no spaces in the middle)

3. check box:

$ ("input[@type =checkbox][@checked]"). Val (); Gets the value of the first item selected in the check box
$ ("input[@type =checkbox][@checked]"). each (function () {//The check box is typically selected for more than one, so you can loop out
 alert ($ (this). Val ());
$ ("#chk1"). attr ("Checked", "")//Do not tick
$ ("#chk2"). attr ("Checked", true);/tick
if ($ ("#chk1"). attr (' checked ') ==undefined) {}//judge whether the tick has been ticked

I hope this article will help you with the jquery program design.