jquery 'on' vs 'delegate'

by Shang-De You

HTML

<div id="section">
</div>

JavaScript

//--假裝他是AJAX--
setTimeout(function(){
  $("#section").html(`
    <input type="button" id="btn" value="click"></input>
  `)

	
},1000)


//--action--
$("#section").delegate("#btn","click",function(){
  alert("click");
})