[英]Cannot get an img element that is dynamically added to a page
假設我試圖在9gag上運行以下代碼,以獲取無限滾動動態添加的圖像。 我試圖弄清楚如何獲取img元素。
//want to do something useful in this function
checkIfImg = function(toCheck){
if (toCheck.is('img')) {
console.log("finaly");
}
else {
backImg = toCheck.css('background-image');
if (backImg != 'none'){
console.log("background fynaly");
}
}
}
//that works just fine, since it is not for dynamic content
//$('*').each(function(){
// checkIfImg($(this));
//})
//this is sums up all my attempts
var observer = new MutationObserver(function (mutations) {
mutations.forEach(function (mutation) {
switch (mutation.type) {
case 'childList':
Array.prototype.forEach.call(mutation.target.children, function (child) {
if ( child.tagName === "IMG" ) {
console.log("img");
}
child.addEventListener( 'load', checkIfImg, false );
console.log("forEachChild");
console.log(child);
checkIfImg($(child));
$(child).each(function(){
console.log("inside each");
console.log($(this));
if ($(this).tagName == "IMG"){
console.log("img");
}
checkIfImg($(this));
})
});
break;
default:
}
});
});
observer.observe(document, {childList: true, subtree: true});
觀察者有很多不同的元素,但是我似乎在其中找不到任何img。
您需要檢查樹深處的img
元素,而不僅是mutation.children
的直接子代(每個子代可能包含其他子代)。
您可以使用$.find('img')
,並使用數組消除重復項:
let imageList = [];
//want to do something useful in this function
function checkIfImg(toCheck) {
// find all images in changed node
let images = toCheck.find('img');
for(let image of images) {
let imageSource = $(image).attr('src');
if(!imageList.includes(imageSource)) {
imageList.push(imageSource);
console.log("image:", imageSource);
}
}
};
// get existing images
checkIfImg($(document));
// observe changes
var observer = new MutationObserver(function(mutations) {
mutations.forEach(mutation => checkIfImg($(mutation.target)));
});
observer.observe(document, { childList: true, subtree: true });
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.