ajax动态加载图片例子

想在网页后期加载图片，简单，如下例子：

var delayPics=$('.delayPics');
var _picNum = delayPics.length;
if(_picNum > 0){
	//!--_picNum
	//delayPics.each(function(index,item){
	$.each(delayPics,function(index,item){
		//$(item).attr("clickable")
		//$(this).trigger("hover",window.event);
		let picid=$(this).data("id");
		
		$.ajax({
		  type: "GET",
		  url: "gopic_subject.php?id="+picid,
		  beforeSend: function (xhr) {
			xhr.overrideMimeType('text/plain; charset=x-user-defined');
		  },
		  success: function (result, textStatus, jqXHR) {       
			if(result.length < 1){
				alert("The thumbnail doesn't exist");
				$(item).attr("src", "data:image/png;base64,");
				return
			}
		
			var binary = "";
			var responseText = jqXHR.responseText;
			var responseTextLen = responseText.length;
		
			for ( i = 0; i < responseTextLen; i++ ) {
				binary += String.fromCharCode(responseText.charCodeAt(i) & 255)
			}
			$(item).attr("src", "data:image/png;base64,"+btoa(binary));
		  },
		  error: function(xhr, textStatus, errorThrown){
			alert("Error in getting document "+textStatus);
		  } 
		});
	});
}