How to judge whether there is a specific child(.haschild('#test[att="test"]')) with jQuery?

<div id="target">
<div id="test" att="test"></di开发者_Go百科v>
</div>

$('target').haschild('#test') should be true

$('target').haschild('#test[att="test"]') should be true

$('target').haschild('#no') should be false

Only $('target') is available.

---

$('target').children('#test').length == 0

or

$('target > #test').length == 0

---

You can test a few ways, here is one:

if($("#target > #test").length){
   //true
} else {
   //false
}

If you play with jQuery plugins, you can actually use the syntax you use in your example:

$.fn.haschild = function(selector){
  return ($("> " + selector, this).length > 0);
}

$(function(){
  alert($('#target').haschild('#test')); // Alerts true
  alert($('#target').haschild('#test[att="test"]'));  // Alerts true
  alert($('#target').haschild('#no'));  // Alerts false
});

Here is a working example

---

Modifying an example found here to suit this example, you can extend JQuery to have a new :haschild selector, as well as the method,

The you can use $('#target:haschild(#test)') as well as .haschild('#test')

$.fn.haschild = function(selector){
      function filterMethod(){
            if (selector) {
                  return $(this).children(selector).length >= 1;
            }
            return $(this).children().length >= 1;            
      }
      return this.filter(filterMethod);
}
$.expr[':'].haschild = function(objNode,intStackIndex,arrProperties,arrNodeStack){      
      var selector = arrProperties[3];
      if (selector) {
            return $(objNode).children(selector).length >= 1;
      }
      return $(objNode).children().length >= 1;
}