Solve the problem of 404 when loading js images_javascript skills

After operating a website for a long time, it is inevitable that image 404 will appear. The reason may be that the image file does not exist or does not currently exist. A common solution is to hide the 404 image or replace it with the default image .
img tag event attribute
The time attributes that can be used in img tags are:
onabort, onbeforeunload, onblur, onchange, onclick, oncontextmenu, ondblclick, ondrag, ondragend, ondragenter, ondragleave, ondragover, ondragstart, ondrop, onerror, onfocus, onkeydown, onkeypress, onkeyup, onload, onmessage, onmousedown, onmousemove, onmouseover, onmouseout, onmouseup, onmousewheel, onresize, onscroll, onselect, onsubmit, onunload
The commonly used events of the img tag are as follows:
onerror: Triggered when an error occurs during image loading.
onabort: When the image is loading, it is triggered when the user clicks to stop loading. It usually triggers a prompt here: "Image is loading".
onload: Triggered when the image is loaded.
1. Monitor onerror events for images

<img src="someimage.png" onerror="imgError(this);" /> 
 
// 原生JS: 
function imgError(image){ 
 // 隐藏图片 
 image.style.display = 'none'; 
 // 替换为默认图片 
 // document.getElementById("img").setAttribute("src", "images/demo.png"); 
} 
 
// 使用jQuery处理: 
function imgError(image){ 
 $(image).hide(); 
 // $(this).attr("src", "images/demo.png"); 
} 

Note: The processing function needs to be defined in the head to prevent the processing function from not being read when an image loading error occurs
2. Use jQuery to monitor errors

// 通常不会再HTML里面内联js，可以使用.error对图片进行监听处理 
$('#test img').error(function() { 
 $(this).hide(); 
 // $(this).attr("src", "images/demo.png"); 
}); 

Note: jQuery loading needs to be before img, and the processing function needs to be after img
3. Use function processing

// 原生JS解决方案 
function $id(id) { 
 return !id || id.nodeType === 1 ? id : document.getElementById(id); 
} 
function isType(o, t) { 
 return (typeof o).indexOf(t.charAt(0).toLowerCase()) === 0; 
} 
 
// 主要逻辑 
function image(src, cfg) { 
 var img, prop, target; 
 cfg = cfg || (isType(src, 'o') ? src : {}); 
 
 img = $id(src); 
 if (img) { 
  src = cfg.src || img.src; 
 } else { 
  img = document.createElement('img'); 
  src = src || cfg.src; 
 } 
 
 if (!src) { 
  return null; 
 } 
 
 prop = isType(img.naturalWidth,'u') ? 'width' : 'naturalWidth'; 
 img.alt = cfg.alt || img.alt; 
 
 // Add the image and insert if requested (must be on DOM to load or 
 // pull from cache) 
 img.src = src; 
 
 target = $id(cfg.target); 
 if (target) { 
  target.insertBefore(img, $id(cfg.insertBefore) || null); 
 } 
 
 // Loaded? 
 if (img.complete) { 
  if (img[prop]) { 
   if (isType(cfg.success,'f')) { 
    cfg.success.call(img); 
   } 
  } else { 
   if (isType(cfg.failure,'f')) { 
    cfg.failure.call(img); 
   } 
  } 
 } else { 
  if (isType(cfg.success,'f')) { 
   img.onload = cfg.success; 
  } 
  if (isType(cfg.failure,'f')) { 
   img.onerror = cfg.failure; 
  } 
 } 
 
 return img; 
} 

The above functions have many uses:
1. Get image information: whether the image can be downloaded, image width and height

image('img',{ 
 success : function () { alert(this.width + "-" + this.height); }, 
 failure : function () { alert('image 404!'); }, 
}); 
 
// 验证资源是否下载 
image('images/banner/banner_2.jpg', { 
 success : function () {console.log('sucess')}, 
 failure : function () {console.log('failure')}, 
 target : 'myContainerId', 
 insertBefore : 'someChildOfmyContainerId' 
}); 

2. Download and insert pictures

var report = $id('report'), 
 callback = { 
  success : function () { 
   report.innerHTML += '<p>Success - ' + this.src + ' ('+this.offsetWidth+'x'+this.offsetHeight+')</p>'; 
  }, 
  failure : function () { 
   report.innerHTML += '<p>Failure - ' + this.src + ' ('+this.offsetWidth+'x'+this.offsetHeight+')</p>'; 
  }, 
  target : 'target' 
 }; 
 
image('img', callback); 
image('images/banner/banner_2.jpg', callback); 

The above is the js solution to the 404 problem when loading images. I hope you can gain something.