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

Question

<div id="target">
<div id="test" att="test"></div>
</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.

Answer 1

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

or

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

Answer 2

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