jquery Determines if check box is checked

A feature check box is checked when the input form is assigned a value, and the check box cancels when the form value is cleared. function: The check box is checked when the input form is assigned a value, and the check box cancels when the form value is cleared.

Implementation Source: Cyfid is the ID of the check box
$ ("#cyfID"). Click (function () { var ischeck=$ (this). attr ("checked");
if (ischeck==undefined) {
Clear the Input box
Alert ("");
}else{
Assigning a value to an input box
Alert ("QQ");
} www.jbxue.com
});
Implementation principle:
check box tick the $ (this). attr ("Checked") is checked and is not checked for undefined.