Jquery knowledge point three jquery form object operation_jquery

In Jquery, if these three functions have parameters, they are assignment operations. If there are no parameters, they are value acquisition operations. Among them, val() is a very important method, and its related form objects such as: input system labels, select, textarea etc. are all tag elements used to interact with the server, so you need to understand this val();
For assignment operations of radio, checkbox, and select:

Copy code The code is as follows:

$("input[name=a]").val(["Entertainment 1"]) ;
$("input[type=checkbox]").val(["Basketball", "Game"]);
$("select").val(["Basketball", "Game"] ; [], if there are multiple values, separate them with commas;
Assign a value to the select and obtain the select through the label selector.

For the value operations of radio, checkbox, and select:



Copy code
The code is as follows:

var checkvalue = ""; var s = $ ("input[name=a]:checked").val(); $(":checkbox:checked").each(function() { checkvalue = $(this).val(); });

var selectvalue = "";

$("select :selected").each(function() {
selectvalue = $(this).val();
});
alert("checkvalue:" checkvalue "radiovalue:" s "selectvalue:" selectvalue);



Code analysis:

declares an s The variable is used to receive the selected value of the radio with name=a. It can also be written as var s=$(":radio:checked").val(). :radio can be understood as the input element of type=radio, which is an attribute. A simplified way of writing a selector;
Get the selected value of the checkbox. Because the checkbox is a multi-select box, each selected item needs to be processed with each. It can also be written according to the attribute selector: $(" input[type=checkbox]:checked");
For select, when the attribute multiple ="multiple", multiple selections can be made. Here, each is also used for traversal processing;

Summary:
For input-based tag elements, we can use the attribute selector to obtain: $("input[type=checkbox]"), or in a concise way: $(":checkbox"), similar ones: : radio, :submit, :image, :reset, :button, :file, :hidden, :password, :text;
$(":input")Select all <select and> elements <br> use:checked for radio and checkbox to obtain the selected item, and for select, use:selected( $("select :selected"), $(":radio:checked") .val();) <br><strong></strong><br><br>Copy code<br><br><br> The code is as follows:<div class="codetitle"><div class="codebody" id="code50241"> <br> <br> <br> <br><title></title> <br><script src="../myjs/jquery-1.4.2-vsdoc.js" type="text/javascript"></script> <br><script type="text/javascript"> <BR>$(function() { <BR>$(":button[value=取值]").click(function() { <BR>var checkvalue = ""; <BR>//var s = $("input[name=a]:checked").val(); <BR>var s = $(":radio:checked").val(); <BR>$("input[type=checkbox]:checked").each(function() { <BR>checkvalue = $(this).val(); <BR>}); <BR>var selectvalue = ""; <BR>$("select :selected").each(function() { <BR>selectvalue = $(this).val(); <BR>}); <BR>alert("checkvalue:" checkvalue "radiovalue:" s "selectvalue:" selectvalue); <BR>}); <BR>$(":button[value=设置]").click(function() { <BR>$("input[name=a]").val(["娱乐1"]); <BR>$("input[type=checkbox]").val(["篮球", "游戏"]); <BR>$("select").val(["篮球", "游戏"]); <BR>}); <BR>}); <br><br></script> <br> <br> <br><input type="checkbox" id="footbal" value="足球"><label for="footbal">足球</label><br> <br><input type="checkbox" value="篮球">篮球<br> <br><input type="checkbox" value="看书">看书<br> <br><input type="checkbox" value="游戏">游戏<br><hr> <br><input type="radio" name="a" id="b" value="娱乐1"><label for="b">娱乐1</label><br> <br><input type="radio" name="a" value="娱乐2">娱乐2<br> <br><input type="radio" name="a" value="娱乐3">娱乐3<br> <br><hr> <br><select multiple> <br><option value="篮球">篮球</option> <br><option value="足球">足球</option> <br><option value="看书">看书</option> <br><option value="游戏">游戏</option> <br></select> <br><input type="button" value="取值"> <input type="button" value="设置"> <br> <br> <br> </div></div></select>